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The snout region of Ankylosaurus was unique among ankylosaurs, and had undergone an "extreme" transformation compared to its relatives. The snout was arched and truncated at the front, and the nostrils were elliptical and were directed downward and outward, unlike in all other known ankylosaurids where they faced obliquely forward or upward. Additionally, the nostrils were not visible from the front because the sinuses were expanded to the sides of the premaxilla bones, to a larger extent than seen in other ankylosaurs. Large loreal caputegulae—strap-like, side osteoderms of the snout—completely roofed the enlarged opening of the nostrils, giving a bulbous appearance. The nostrils also had an intranarial septum, which separated the nasal passage from the sinus. Each side of the snout had five sinuses, four of which expanded into the maxilla bone. The nasal cavities (or chambers) of Ankylosaurus were elongated and separated by a septum at the midline, which divided the inside of the snout into two mirrored halves. The nasal chambers had two openings, including the choanae (internal nostrils), and the air passage was looped. The maxillae expanded to the sides, giving the impression of a bulge, which may have been due to the sinuses inside. The maxillae had a ridge that may have been the attachment site for fleshy cheeks; the presence of cheeks in ornithischians is controversial, but some nodosaurs had armor plates that covered the cheek region, which may have been embedded in the flesh. | Ankylosaurus | Wikipedia | 334 | 983374 | https://en.wikipedia.org/wiki/Ankylosaurus | Biology and health sciences | Ornitischians | Animals |
Specimen AMNH 5214 has 34–35 dental alveoli (tooth sockets) in the maxilla. The tooth rows in the maxillae of this specimen are about long. Each alveolus had a foramen (opening) near its side where a replacement tooth could be seen. Compared to other ankylosaurs, the mandible of Ankylosaurus was low in proportion to its length, and, when seen from the side, the tooth row was almost straight instead of arched. The mandibles are completely preserved only in the smallest specimen (AMNH 5214) and are about long. The incomplete mandible of the largest specimen (CMN 8880) is the same length. AMNH 5214 has 35 dental alveoli in the left dentary bone () and 36 in the right, for a total of 71. The predentary bone of the tip of the mandibles has not yet been found. Like other ankylosaurs, Ankylosaurus had small, phylliform (leaf-shaped) teeth, which were compressed sideways. The teeth were mostly taller than they were wide, and were very small; their size in proportion to the skull meant that the jaws of Ankylosaurus could accommodate more teeth than other ankylosaurines. The teeth of the largest Ankylosaurus skull are smaller than those of the smallest skull in the absolute sense. Some teeth from behind in the tooth row curved backwards, and tooth crowns were usually flatter on one side than the other. Ankylosaurus teeth are diagnostic and can be distinguished from the teeth of other ankylosaurids based on their smooth sides. The denticles were large, their number ranging from six to eight on the front part of the tooth, and five to seven behind.
Postcranial skeleton | Ankylosaurus | Wikipedia | 376 | 983374 | https://en.wikipedia.org/wiki/Ankylosaurus | Biology and health sciences | Ornitischians | Animals |
The structure of much of the skeleton of Ankylosaurus, including most of the pelvis, tail, and feet, is still unknown. It was quadrupedal, and its hind limbs were longer than its forelimbs. In the holotype specimen, the scapula (shoulder blade) measures long and was fused with the coracoid (a rectangular bone connected to the lower end of the scapula). It also had entheses (connective tissue) for various muscle attachments. The humerus (upper arm bone) of AMNH 5214 was short, very broad and about long. The femur (thigh bone), also from AMNH 5214, was long and very robust. While the feet of Ankylosaurus are incompletely known, the hindfeet probably had three toes, as is the case in advanced ankylosaurids.
The cervical vertebrae had broad neural spines that increased in height towards the body. The front part of the neural spines had well-developed entheses, which was common among adult dinosaurs, and indicates the presence of large ligaments, which helped support the massive head. The dorsal vertebrae had centra (or bodies) that were short relative to their width, and their neural spines were short and narrow. The dorsal vertebrae were tightly spaced, which limited the downwards movement of the back. The neural spines had ossified (turned to bone) tendons, which also overlapped some of the vertebrae. The ribs of the last four back vertebrae were fused to the and (the structures that articulated the ribs with the vertebrae), and the ribcage was very broad in this part of the body. The caudal vertebrae had centra that were slightly amphicoelous, meaning they were concave on both sides. | Ankylosaurus | Wikipedia | 368 | 983374 | https://en.wikipedia.org/wiki/Ankylosaurus | Biology and health sciences | Ornitischians | Animals |
Armor
A prominent feature of Ankylosaurus was its armor, consisting of knobs and plates of bone known as osteoderms, or scutes, embedded in the skin. These have not been found in articulation, so their exact placement on the body is unknown, though inferences can be made based on related animals, and various configurations have been proposed. The osteoderms ranged from in diameter to in length, and varied in shape. The osteoderms of Ankylosaurus were generally thin walled and hollowed on the underside. Compared to Euoplocephalus, the osteoderms of Ankylosaurus were smoother. Many smaller osteoderms and ossicles probably occupied the space between the larger ones, as in other ankylosaurids. The osteoderms covering the body were very flat, though with a low keel at one margin. In contrast, the nodosaurid Edmontonia had high keels stretching from one margin to the other on the midline of its osteoderms. Ankylosaurus had some smaller osteoderms with a keel across the midline. | Ankylosaurus | Wikipedia | 238 | 983374 | https://en.wikipedia.org/wiki/Ankylosaurus | Biology and health sciences | Ornitischians | Animals |
Like other ankylosaurids, Ankylosaurus had (armor plates on the neck), but these are known only from fragments, making their exact arrangement uncertain. Carpenter suggested that when seen from above, the plates would have been paired, creating an inverted V-shape across the neck, with the midline gap probably being filled with small ossicles (round bony scutes) to allow for movement. He believed the width of this armor belt was too wide to have fitted solely on the neck, and that it covered the base of the neck and continued onto the shoulder region. Arbour and the Canadian paleontologist Philip J. Currie disagreed with Carpenter's interpretation in 2015 and pointed out that the cervical half-ring fragments of the holotype specimen did not fit together in the way proposed by Carpenter (though this could be due to breakage). They instead suggested that the fragments represented the remains of two cervical half-rings, which formed two semi-circular plates of armor around the upper part of the neck, as in the closely related Anodontosaurus and Euoplocephalus. Arbour and Mallon elaborated on this idea, describing the shape of these half-rings as "continuous U-shaped yokes" over the upper part of the neck, and suggested that Ankylosaurus had six keeled osteoderms with oval bases on each half-ring. | Ankylosaurus | Wikipedia | 286 | 983374 | https://en.wikipedia.org/wiki/Ankylosaurus | Biology and health sciences | Ornitischians | Animals |
The first osteoderms behind the second cervical half-ring would have been similar in shape to those in the first half-ring, and the osteoderms on the back probably decreased in diameter hindwards. The largest osteoderms were probably arranged in transverse and longitudinal rows across most of the body, with four or five transverse rows separated by creases in the skin. The osteoderms on the flanks would probably have had a more square outline than those on the back. There may have been four longitudinal rows of osteoderms on the flanks. Unlike some basal ankylosaurs and many nodosaurs, ankylosaurids do not appear to have had co-ossified pelvic shields above their hips. Some osteoderms without keels may have been placed above the hip region of Ankylosaurus, as in Euoplocephalus. Ankylosaurus may have had three or four transverse rows of circular osteoderms over the pelvic region, which were smaller than those on the rest of the body, as in Scolosaurus. Smaller, triangular osteoderms may have been present on the sides of the pelvis. Flattened, pointed plates resemble those on the sides of the tail of Saichania, and may have been distributed similarly on Ankylosaurus. Osteoderms with oval keels could have been placed on the upper side of the tail or the side of the limbs. Compressed, triangular osteoderms found with Ankylosaurus specimens may have been placed on the sides of the pelvis or the tail. Ovoid, keeled, and teardrop-shaped osteoderms are known from Ankylosaurus, and may have been placed on the forelimbs, like those known from Pinacosaurus, but it is unknown whether the hindlimbs bore osteoderms. | Ankylosaurus | Wikipedia | 391 | 983374 | https://en.wikipedia.org/wiki/Ankylosaurus | Biology and health sciences | Ornitischians | Animals |
The tail club (or tail knob) of Ankylosaurus was composed of two large osteoderms, with a row of small osteoderms at the midline, and two small osteoderms at the tip; these osteoderms obscured the last tail vertebra. As only the tail club of specimen AMNH 5214 is known, the range of variation between individuals is unknown. The tail club of AMNH 5214 is long, wide, and tall. The club of the largest specimen may have been wide. The tail club of Ankylosaurus was semicircular when seen from above, similar to those of Euoplocephalus and Scolosaurus but unlike the pointed club osteoderms of Anodontosaurus or the narrow, elongated club of Dyoplosaurus. The last seven tail vertebrae formed the "handle" of the tail club. These vertebrae were in contact, with no cartilage between them, and were sometimes co-ossified, which made them immobile. Ossified tendons attached to the vertebrae in front of the tail club, and these features together helped strengthen it. The interlocked zygapophyses (articular processes) and neural spines of the handle vertebrae were U-shaped when seen from above, whereas those of most other ankylosaurids are V-shaped, which may be due to the handle of Ankylosaurus being wider. The larger width may indicate that the tail of Ankylosaurus was shorter in relation to its body length than those of other ankylosaurids, or that it had the same proportions but with a smaller club. | Ankylosaurus | Wikipedia | 342 | 983374 | https://en.wikipedia.org/wiki/Ankylosaurus | Biology and health sciences | Ornitischians | Animals |
Classification
Brown considered Ankylosaurus so distinct that he made it the type genus of a new family, Ankylosauridae, typified by massive, triangular skulls, short necks, stiff backs, broad bodies, and osteoderms. He also classified Palaeoscincus (only known from teeth), and Euoplocephalus (then only known from a partial skull and osteoderms) as part of the family. Due to the fragmentary condition of the remains, Brown was unable to fully distinguish between Euoplocephalus and Ankylosaurus. Having for comparison only a few, incomplete members of the family, he believed the group was part of the suborder Stegosauria. In 1923 Osborn coined the name Ankylosauria, thereby placing the ankylosaurids in their own suborder.
Ankylosauria and Stegosauria are now grouped together within the clade Thyreophora. This group first appeared in the Sinemurian age, and survived for 135 million years until disappearing in the Maastrichtian. They were widespread and inhabited a broad range of environments. As more complete specimens and new genera have been discovered, theories about ankylosaurian interrelatedness have become more complex, and hypotheses have often changed between studies. In addition to Ankylosauridae, Ankylosauria has been divided into the families Nodosauridae, and sometimes Polacanthidae (these families lacked tail clubs). Ankylosaurus is considered part of the subfamily Ankylosaurinae (members of which are called ankylosaurines) within Ankylosauridae. Ankylosaurus appears to be most closely related to Anodontosaurus and Euoplocephalus. The following cladogram is based on a 2015 phylogenetic analysis of the Ankylosaurinae conducted by Arbour and Currie: | Ankylosaurus | Wikipedia | 398 | 983374 | https://en.wikipedia.org/wiki/Ankylosaurus | Biology and health sciences | Ornitischians | Animals |
Because Ankylosaurus and other Late Cretaceous North American ankylosaurids were grouped with Asian genera (in a tribe the authors named Ankylosaurini), Arbour and Currie suggested that earlier North American ankylosaurids had gone extinct by the late Albian or Cenomanian ages of the Middle Cretaceous. Ankylosaurids thereafter recolonized North America from Asia during the Campanian or Turonian ages of the Late Cretaceous, and there diversified again, leading to genera such as Ankylosaurus, Anodontosaurus, and Euoplocephalus. The theory explains a 30-million-year gap in the fossil record of North American ankylosaurids between the ages.
Paleobiology
Feeding
Like other ornithischians, Ankylosaurus was herbivorous. Its wide muzzle was adapted for non-selective low-browse cropping, although not to the extent seen in some related genera, especially Euoplocephalus. Though ankylosaurs may not have fed on fibrous and woody plants, they may have had a varied diet, including tough leaves and pulpy fruits. Ankylosaurus probably fed on abundant ferns and low-growing shrubs. Assuming it was endothermic, Ankylosaurus would have eaten of ferns per day, similar to the amount of dry vegetation a large elephant would consume. The requirements for nutrition could have been more effectively met if Ankylosaurus ate fruit, which its small, cusp-like teeth and the shape of its beak seem well adapted for, compared to for example Euoplocephalus. Certain invertebrates, which the small teeth may have been adapted for handling, could also have provided supplemental nutrition. | Ankylosaurus | Wikipedia | 358 | 983374 | https://en.wikipedia.org/wiki/Ankylosaurus | Biology and health sciences | Ornitischians | Animals |
Fossils of Ankylosaurus teeth exhibit wear on the face of the crown rather than on the tip of the crown, as in nodosaurid ankylosaurs. In 1982 Carpenter ascribed to baby Ankylosaurus two very small teeth that originate from the Lance and Hell Creek Formations and measure in length, respectively. The smaller tooth is heavily worn, leading Carpenter to suggest that ankylosaurids in general or at least the young did not swallow their food whole but employed some sort of chewing. Since adult Ankylosaurus did little chewing of its food, it would have spent less time in the day foraging than an elephant. Based on the broadness of the ribcage, the digestion of unchewed food may have been facilitated by hindgut fermentation like in modern herbivorous lizards, which have several chambers in their enlarged colon.
In 1969, paleontologist Georg Haas concluded that despite the large size of ankylosaur skulls, the associated musculature was relatively weak. He also thought jaw movement was limited to up and down movements. Extrapolating from this, Haas suggested that ankylosaurs ate relatively soft non-abrasive vegetation. Later research on Euoplocephalus indicates that forward and sideways jaw movement was possible in these animals, the skull being able to withstand considerable forces. A 2016 study of the dental occlusion (contact between the teeth) of ankylosaur specimens found that the ability for backwards (palinal) jaw movement evolved independently in different ankylosaur lineages, including Late Cretaceous North American ankylosaurids like Ankylosaurus and Euoplocephalus. | Ankylosaurus | Wikipedia | 342 | 983374 | https://en.wikipedia.org/wiki/Ankylosaurus | Biology and health sciences | Ornitischians | Animals |
The retracted position of the nostrils of Ankylosaurus were compared to those of fossorial (digging) worm lizards and blind snakes by Arbour and Mallon in 2017, and though it was probably not a burrowing animal, the snout of Ankylosaurus may indicate earth-moving behavior. These factors, as well as the low rate of tooth formation in ankylosaurs compared to other ornithischians, indicate that Ankylosaurus may have been omnivorous (eating both plant and animal matter). It may also (or alternatively) have dug in the ground for roots and tubers. A 2023 study by paleontologist Antonio Ballell and colleagues found that North American ankylosaurids from the latest Cretaceous (including Ankylosaurus) had jaws with low mechanical advantage, whereas those of earlier relatives were high to moderate. These late ankylosaurids also had tooth occlusion and complex biphasal jaw mechanisms, features shared with some Late Cretaceous nodosaurids, but those instead have jaws with high mechanical advantage. This indicates that while the two groups converged in some features, the nodosaurs had higher relative bite force, which suggests diverging jaw mechanics and dietary partitioning between the two.
Airspaces and senses
In 1977, paleontologist Teresa Maryańska proposed that the complex sinuses and nasal cavities of ankylosaurs may have lightened the weight of the skull, housed a nasal gland, or acted as a chamber for vocal resonance. Carpenter rejected these hypotheses, arguing that tetrapod animals make sounds through the larynx, not the nostrils, and that reduction in weight was minimal, as the spaces only accounted for a small percent of the skull volume. He also considered a gland unlikely and noted that the sinuses may not have had any specific function. It has also been suggested that the respiratory passages were used to perform a mammal-like treatment of inhaled air, based on the presence and arrangement of specialized bones. | Ankylosaurus | Wikipedia | 411 | 983374 | https://en.wikipedia.org/wiki/Ankylosaurus | Biology and health sciences | Ornitischians | Animals |
A 2011 study of the nasal passages of Euoplocephalus by paleontologist Tetsuto Miyashita and colleagues supported their function as a heat and water balancing system, noting the extensive blood vessel system and an increased surface area for the mucosa membrane (used for heat and water exchange in modern animals). The researchers also supported the idea of the loops acting as a resonance chamber, comparable to the elongated nasal passages of saiga antelope and the looping trachea of cranes and swans. Reconstructions of the inner ear suggest adaptation to hearing at low frequencies, such as the low-toned resonant sounds possibly produced by the nasal passages. They disputed the possibility that the looping is related to olfaction (sense of smell) as the olfactory region is pushed to the sides of the main airway.
According to Carpenter, the shape of the nasal chambers of Ankylosaurus indicate that airflow was unidirectional (looping through the lungs during inhalation and exhalation), although it may also have been bidirectional in the posterior nasal chamber, with air directed past the olfactory lobes. The enlarged olfactory region of ankylosaurids indicates a well-developed sense of smell. Though hindwards retraction of the nostrils is seen in aquatic animals and animals with a proboscis, it is unlikely either possibility applies to Ankylosaurus, as the nostrils tend to be reduced or the premaxilla extended. In addition, though the widely separated nostrils may have allowed for stereo-olfaction (where each nostril senses smells from different directions), as has been proposed for the moose, little is known about this feature. The position of the orbits of Ankylosaurus suggest some stereoscopic vision.
Limb movements
Reconstructions of ankylosaur forelimb musculature made by Coombs in 1978 suggest that the forelimbs bore the majority of the animal's weight, and were adapted for high force delivery on the front feet, possibly for food gathering. In addition, Coombs suggested that ankylosaurs may have been capable diggers, though the hoof-like structure of the manus would have limited fossorial activity. Ankylosaurs were likely to have been slow-moving and sluggish animals, though they may have been capable of quick movements when necessary. | Ankylosaurus | Wikipedia | 494 | 983374 | https://en.wikipedia.org/wiki/Ankylosaurus | Biology and health sciences | Ornitischians | Animals |
Growth
The squamosal horns of the largest Ankylosaurus specimen are blunter than those of the smallest specimen, which is also the case in Euoplocephalus, and this may represent ontogenetic variation (related to growth development). Studies of specimens of Pinacosaurus of different ages found that during ontogenetic development, the ribs of juvenile ankylosaurs fused with their vertebrae. The forelimbs strongly increased in robustness while the hindlimbs did not become larger relative to the rest of the skeleton, further evidence that the arms bore most of the weight. In the cervical half-rings, the underlying bone band developed outgrowths connecting it with the underlying osteoderms, which simultaneously fused to each other. On the skull, the middle bone plates first ossified at the snout and the rear rim, with ossification gradually extending towards the middle regions. On the rest of the body, ossification progressed from the neck backward in the direction of the tail.
Defense
The osteoderms of ankylosaurids were thin in comparison to those of other ankylosaurs, and appear to have been strengthened by randomly distributed cushions of collagen fibers. Structurally similar to Sharpey's fibres, they were embedded directly into the bone tissue, a feature unique to ankylosaurids. This would have provided the ankylosaurids with an armor covering that was both lightweight and highly durable, being resistant to breakage and penetration by the teeth of predators. The palpebral bones over the eyes may have provided additional protection for them. Carpenter suggested in 1982 that the heavily vascularized armor may also have had a role in thermoregulation as in modern crocodilians.
The tail club of Ankylosaurus seems to have been an active defensive weapon, capable of producing enough of an impact to break the bones of an assailant. The tendons of the tail were partially ossified and were not very elastic, allowing great force to be transmitted to the club when it was used as a weapon. Coombs suggested in 1979 that several hindlimb muscles would have controlled the swinging of the tail, and that violent thrusts of the club would have been able to break the metatarsal bones of large theropods. | Ankylosaurus | Wikipedia | 474 | 983374 | https://en.wikipedia.org/wiki/Ankylosaurus | Biology and health sciences | Ornitischians | Animals |
A 2009 study estimated that ankylosaurids could swing their tails at 100 degrees laterally, and the mainly cancellous clubs would have had a lowered moment of inertia and been effective weapons. The study also found that while adult ankylosaurid tail clubs were capable of breaking bones, those of juveniles were not. Despite the feasibility of tail-swinging, the researchers could not determine whether ankylosaurids used their clubs for defense against potential predators, in intraspecific combat, or both. Other studies have found evidence of ankylosaurids using their tail clubs for intraspecific combat. One specimen of Tarchia showed signs of injury on both the pelvic and tail area and the club was found to be asymmetrical, a sign of being worn down by the strikes.
In 1993, Tony Thulborn proposed that the tail club of ankylosaurids primarily acted as a decoy for the head, as he thought the tail too short and inflexible to have an effective reach; the "dummy head" would lure a predator close to the tail, where it could be struck. Carpenter has rejected this idea, as tail club shape is highly variable among ankylosaurids, even in the same genus.
Paleoenvironment
Ankylosaurus existed between 68 and 66 million years ago, in the final, or Maastrichtian, stage of the Late Cretaceous Period. It was among the last dinosaur genera that appeared before the Cretaceous–Paleogene extinction event. The type specimen is from the Hell Creek Formation of Montana, while other specimens have been found in the Lance and Ferris Formations in Wyoming, the Scollard Formation in Alberta, and the Frenchman Formation in Saskatchewan, all of which date to the end of the Cretaceous. | Ankylosaurus | Wikipedia | 367 | 983374 | https://en.wikipedia.org/wiki/Ankylosaurus | Biology and health sciences | Ornitischians | Animals |
Fossils of Ankylosaurus are rare in the sediments it is known from, and the distribution of its remains suggests that it was ecologically rare, or restricted to the uplands of the formations, where it would have been less likely to fossilize, rather than the coastal lowlands. Another ankylosaur, a nodosaur referred to as Edmontonia sp., is also found in the same formations, but according to Carpenter, the range of the two genera does not seem to have overlapped. Their remains have so far not been found in the same localities, and the nodosaur appears to have inhabited the lowlands. The narrower muzzle of the nodosaur suggests it had a more selective diet than Ankylosaurus, further indicating ecological separation, whether their range overlapped or not.
With its low center of gravity, Ankylosaurus would have been unable to knock down trees like modern elephants do. It was also incapable of chewing bark and thus unlikely to have practiced bark stripping. As an adult, Ankylosaurus does not appear to have congregated in groups (though some ankylosaurs appear to have congregated when young). It is therefore improbable that Ankylosaurus was able to modify the landscape of its ecosystem in the way elephants do; hadrosaurids may instead have had such an "ecosystem engineer" role. | Ankylosaurus | Wikipedia | 280 | 983374 | https://en.wikipedia.org/wiki/Ankylosaurus | Biology and health sciences | Ornitischians | Animals |
The formations where Ankylosaurus fossils have been found represent different sections of the western shore of the Western Interior Seaway dividing western and eastern North America during the Cretaceous, a broad coastal plain extending westward from the seaway to the newly formed Rocky Mountains. These formations are composed largely of sandstone and mudstone, which have been attributed to floodplain environments. The regions where Ankylosaurus and other Late Cretaceous ankylosaurs have been found had a warm subtropical/temperate climate, which was monsoonal, had occasional rainfall, tropical storms, and forest fires. In the Hell Creek Formation, many types of plants were supported, primarily angiosperms, with less common conifers, ferns and cycads. An abundance of fossil leaves found at dozens of different sites indicates that the area was largely forested by small trees. Ankylosaurus shared its environment with other dinosaurs that included the ceratopsids Triceratops and Torosaurus, the hypsilophodont Thescelosaurus, the hadrosaurid Edmontosaurus, an indeterminate nodosaur, the pachycephalosaurian Pachycephalosaurus, and the theropods Struthiomimus, Ornithomimus, Pectinodon, and Tyrannosaurus.
Cultural significance
Carpenter noted in 2004 that Ankylosaurus has become the archetypal member of its group, and the best-known ankylosaur in popular culture, perhaps due to a life-sized reconstruction of the animal being featured at the 1964 World's Fair in New York City. Arbour and Mallon called Ankylosaurus an "iconic" dinosaur in 2017, and noted that the World's Fair sculpture, as well as the American artist Rudolph Zallinger's 1947 mural The Age of Reptiles and other later popular depictions, showed Ankylosaurus with a tail club, following the first discovery of the feature in 1910. | Ankylosaurus | Wikipedia | 398 | 983374 | https://en.wikipedia.org/wiki/Ankylosaurus | Biology and health sciences | Ornitischians | Animals |
Many traditional popular depictions show Ankylosaurus in a squatting posture and with a huge tail club being dragged over the ground. Modern reconstructions show the animal with a more upright limb posture and with the tail held off the ground. Likewise, large spines projecting sideways from the body (similar to those of nodosaurid ankylosaurs) are present in many traditional depictions, but are not known from Ankylosaurus itself. The armor of Ankylosaurus has often been conflated with that of Edmontonia (earlier referred to as Palaeoscincus); in addition to Ankylosaurus being depicted with spikes, Edmontonia has also been depicted with an Ankylosaurus-like tail club (a feature nodosaurids did not have), including in a mural by the American artist Charles R. Knight from 1930. Ankylosaurus has been featured in the Jurassic Park franchise, where they are depicted as attacking with their tails and running, abilities that have been criticized as unlikely by paleontologists. | Ankylosaurus | Wikipedia | 211 | 983374 | https://en.wikipedia.org/wiki/Ankylosaurus | Biology and health sciences | Ornitischians | Animals |
47 Tucanae or 47 Tuc (also designated as NGC 104 and Caldwell 106) is a globular cluster located in the constellation Tucana. It is about from Earth, and 120 light years in diameter. 47 Tuc can be seen with the naked eye, with an apparent magnitude of 4.1. It appears about 44 arcminutes across including its far outreaches. Due to its far southern location, 18° from the south celestial pole, it was not catalogued by European astronomers until the 1750s, when the cluster was first identified by Nicolas-Louis de Lacaille from South Africa.
47 Tucanae is the second brightest globular cluster after Omega Centauri, and telescopically reveals about ten thousand stars, many appearing within a small dense central core. The cluster may contain an intermediate-mass black hole.
Early history
The cluster was recorded in 1751-2 by Nicolas-Louis de Lacaille, who initially thought it was the nucleus of a bright comet. Lacaille then listed it as "Lac I-1", the first object listed in his deep-sky catalogue. The number "47" was assigned in Allgemeine Beschreibung und Nachweisung der Gestirne nebst Verzeichniss ("General description and verification of the stars and indexes"), compiled by Johann Elert Bode and published in Berlin in 1801. Bode did not observe this cluster himself, but had reordered Lacaille's catalogued stars by constellation in order of right ascension.
In the 19th century, Benjamin Apthorp Gould assigned the Greek letter ξ (Xi) to the cluster to designate it ξ Tucanae, but this was not widely adopted and it is almost universally referred to as 47 Tucanae.
Characteristics
47 Tucanae is the second brightest globular cluster in the sky (after Omega Centauri), and is noted for having a small very bright and dense core. It is one of the most massive globular clusters in the Galaxy, containing millions of stars. The cluster appears roughly the size of the full moon in the sky under ideal conditions. Though it appears adjacent to the Small Magellanic Cloud, the latter is some distant, being over fifteen times farther than 47 Tuc. | 47 Tucanae | Wikipedia | 475 | 983423 | https://en.wikipedia.org/wiki/47%20Tucanae | Physical sciences | Notable star clusters | Astronomy |
A blue giant star with a spectral class of B8III is the brightest star in visible and ultraviolet light, with a luminosity of about 1,100 times that of the Sun, and is aptly known as the "Bright Star". It is a post-AGB star, having passed the asymptotic giant branch phase of its life, and is currently fusing helium. It has an effective temperature of about 10,850 K, and is about 54% the mass of the Sun.
The core of 47 Tuc was the subject of a major survey for planets, using the Hubble Space Telescope to look for partial eclipses of stars by their planets. No planets were found, though ten to fifteen were expected based on the rate of planet discoveries around stars near the Sun. This indicates that planets are relatively rare in globular clusters. A later ground-based survey in the uncrowded outer regions of the cluster also failed to detect planets when several were expected. This strongly indicates that the low metallicity of the environment, rather than the crowding, is responsible.
47 Tucanae contains at least two stellar populations of stars, of different ages or metallicities. The dense core contains a number of exotic stars of scientific interest, including at least 21 blue stragglers. Globular clusters efficiently sort stars by mass, with the most massive stars falling to the center. | 47 Tucanae | Wikipedia | 283 | 983423 | https://en.wikipedia.org/wiki/47%20Tucanae | Physical sciences | Notable star clusters | Astronomy |
47 Tucanae contains hundreds of X-ray sources, including stars with enhanced chromospheric activity due to their presence in binary star systems, cataclysmic variable stars containing white dwarfs accreting from companion stars and low-mass X-ray binaries containing neutron stars that are not currently accreting, but can be observed by the X-rays emitted from the hot surface of the neutron star.
47 Tucanae has 35 known millisecond pulsars, the second largest population of pulsars in any globular cluster, after Terzan 5.
These pulsars are thought to be spun up by the accretion of material from binary companion stars, in a previous X-ray binary phase. The companion of one pulsar in 47 Tucanae, 47 Tuc W, seems to still be transferring mass towards its companion, indicating that this system is completing a transition from being an accreting low-mass X-ray binary to a millisecond pulsar. X-ray emission has been individually detected from most millisecond pulsars in 47 Tucanae with the Chandra X-ray Observatory, likely emission from the neutron star surface, and gamma-ray emission has been detected with the Fermi Gamma-ray Space Telescope from its millisecond pulsar population (making 47 Tucanae the first globular cluster to be detected in gamma-rays).
Possible central black hole
It is not yet clear whether 47 Tucanae hosts a central black hole. Hubble Space Telescope data constrain the mass of any possible black hole at the cluster's center to be less than approximately 1,500 solar masses. However, in February, 2017, astronomers announced that a black hole of some 2,200 solar masses may be located in the cluster; the researchers detected the black hole's signature from the motions and distributions of pulsars in the cluster. Despite this, a recent analysis of an updated and more extensive timing data set on these pulsars provides no solid evidence in favor of the existence of a black hole.
Modern discoveries
In December 2008, Ragbir Bhathal of the University of Western Sydney claimed the detection of a strong laser-like signal from the direction of 47 Tucanae. | 47 Tucanae | Wikipedia | 468 | 983423 | https://en.wikipedia.org/wiki/47%20Tucanae | Physical sciences | Notable star clusters | Astronomy |
In May 2015, the first evidence of the process of mass segregation in this globular cluster was announced. The cluster's Hertzsprung–Russell diagram suggests stars approximately 13 billion years old, which is unusually old. | 47 Tucanae | Wikipedia | 47 | 983423 | https://en.wikipedia.org/wiki/47%20Tucanae | Physical sciences | Notable star clusters | Astronomy |
NGC 6946, sometimes referred to as the Fireworks Galaxy, is a face-on intermediate spiral galaxy with a small bright nucleus, whose location in the sky straddles the boundary between the northern constellations of Cepheus and Cygnus. Its distance from Earth is about 25.2 million light-years or 7.72 megaparsecs, similar to the distance of M101 (NGC 5457) in the constellation Ursa Major. Both were once considered to be part of the Local Group, but are now known to be among the dozen bright spiral galaxies near the Milky Way but beyond the confines of the Local Group. NGC 6946 lies within the Virgo Supercluster.
The galaxy was discovered by William Herschel on 9 September 1798. Based on an estimation by the Third Reference Catalogue of Bright Galaxies (RC3) in 1991, the galaxy has a D25 B-band isophotal diameter of . It is heavily obscured by interstellar matter due to its location close to the galactic plane of the Milky Way. Due to its prodigious star formation it has been classified as an active starburst galaxy. NGC 6946 has also been classified as a double-barred spiral galaxy, with the inner, smaller bar presumably responsible for funneling gas into its center.
Various unusual celestial objects have been observed within NGC 6946. This includes the so-called 'Red Ellipse' along one of the northern arms that looks like a super-bubble or very large supernova remnant, and which may have been formed by an open cluster containing massive stars. There are also two regions of unusual dark lanes of nebulosity, while within the spiral arms several regions appear devoid of stars and gaseous hydrogen, some spanning up to two kiloparsecs across. A third peculiar object, discovered in 1967, is now known as "Hodge's Complex". This was once thought to be a young supergiant cluster, but in 2017 it was conjectured to be an interacting dwarf galaxy superimposed on NGC 6946. | NGC 6946 | Wikipedia | 417 | 983904 | https://en.wikipedia.org/wiki/NGC%206946 | Physical sciences | Notable galaxies | Astronomy |
Supernovae
Ten supernovae have been observed in NGC 6946 in the 20th and early 21st century: SN 1917A, SN 1939C, SN 1948B, SN 1968D, SN 1969P, SN 1980K, SN 2002hh, SN 2004et, SN 2008S, and SN 2017eaw. For this reason, NGC 6946 has sometimes been referred to as the "Fireworks Galaxy". This is about ten times the rate observed in our Milky Way galaxy, even though the Milky Way has twice as many stars as NGC 6946.
On 27 September 2004, the Type II supernova SN 2004et was observed at magnitude 15.2 and rose to a maximum visual magnitude of 12.7. Images taken during the preceding days revealed that the supernova explosion occurred on 22 September. The progenitor of the supernova was identified on earlier images –– only the seventh time that such an event was directly identified with its host star. The red supergiant progenitor had an initial mass of about 15 in an interacting binary system shared with a blue supergiant.
During 2009, a bright star within NGC 6946 flared up over several months to become over one million times as bright as the Sun. Shortly thereafter it faded rapidly. Observations with the Hubble Space Telescope suggest that the star did not survive, although there remains some infrared emission from its position. This is thought to come from debris falling onto a black hole that formed when the star died. This potential black hole-forming star is designated N6946-BH1. The progenitor is believed to have been a yellow hypergiant star.
In May 2017, supernova SN 2017eaw was detected in the northwest region of the galaxy, and light curves obtained over the next 600 days showed that it was a Type II-P. The progenitor was determined to have been a red supergiant, with a mass of around 15.
As of 2017, more supernovae had been seen in NGC 6946 than in any other galaxy, a record that has since been surpassed by NGC 3690.
Gallery | NGC 6946 | Wikipedia | 438 | 983904 | https://en.wikipedia.org/wiki/NGC%206946 | Physical sciences | Notable galaxies | Astronomy |
Physignathus cocincinus is a species of agamid lizard native to southern China and mainland Southeast Asia. It is commonly known as the Chinese water dragon, Indochinese water dragon, Asian water dragon, Thai water dragon, or green water dragon.
Chinese water dragons are large diurnal lizards adapted for dense subtropical forests replete with unpolluted streams. They are semi-arboreal, roosting at night on branches overlooking streams, which offer an escape route when the lizards are disturbed. Arthropods are their main source of food, though worms, snails, vertebrates, and plants make up a notable portion of the diet as well. Males are territorial towards each other and bear display features such as crests and jowls. Females are oviparous and reproduce sexually in the wild, though at least one captive Chinese water dragon is known to have reproduced via parthenogenesis. Physignathus cocincinus is related to Australasian lizards in the subfamily Amphibolurinae. One amphibolurine, the Australian water dragon (Intellagama lesuerii) is so anatomically and ecologically similar to Physignathus cocincinus that it was once (erroneously) placed in the same genus.
Feral populations introduced to Hong Kong and Taiwan flourish in high densities despite countermeasures in the latter territory. Their populations are also stable (albeit not widespread) in protected areas of Thailand. However, in the rest of their native range, Chinese water dragons have seen sharp population declines in recent decades. They are listed as a Vulnerable species at risk of extinction in the future, based on current trends. The largest threat to the species is overharvesting for meat and the pet trade. Their meat is in high demand in Vietnam, and captive breeding is currently incapable of replacing wild collection by hunters and poachers. Due to their charismatic appearance, captured Chinese water dragons are sold as pets for both local and international markets. Yearly exports to the European Union and the United States number in the tens of thousands, all of which are taken from wild populations. Habitat loss is another source of pressure, as undisturbed streamside forest is converted into cropland or subjected to illegal logging and other human activities.
Taxonomy | Chinese water dragon | Wikipedia | 468 | 2991134 | https://en.wikipedia.org/wiki/Chinese%20water%20dragon | Biology and health sciences | Iguania | Animals |
The species and genus were first described by Georges Cuvier in 1829. Cuvier's original spelling, Phyhignat,us cocincinus, is likely a printing error. The epithet cocincinus is from the French term , for the type locality Cochin-china (an exonym of Vietnam).
During the 19th and 20th centuries, several other species of agamid lizards were placed in Cuvier's genus Physignathus. These have been reclassified into separate genera, leaving Physignathus with only the original species P. cocincinus remaining. For example, the Australian water dragon (Intellagama lesueurii) was known as Physignathus lesueurii for much of its history.
According to most genetic analyses, Physignathus cocincinus is the sister taxon or the most basal (earliest branching) species of the agamid subfamily Amphibolurinae. All other amphibolurines are native to Australia or New Guinea, including bearded dragons (Pogona spp.), the frilled lizard (Chlamydosaurus kingii), the thorny devil (Moloch horridus), the Australian water dragon, and many others. A 2000 paper estimated that Physignathus cocincinus diverged from the Australasian amphibolurines up to 120 million years ago, though subsequent studies support a more recent divergence, around 30 million years ago. | Chinese water dragon | Wikipedia | 309 | 2991134 | https://en.wikipedia.org/wiki/Chinese%20water%20dragon | Biology and health sciences | Iguania | Animals |
Description
Adult Chinese water dragons are large and robust lizards; males can grow up to 90 cm (3 feet) in total length, including the tail. The tail is very long, exceeding 70% of the total body length. The maximum snout-vent length (tail excluded) is about 25 cm (9.8 inches) in males and 20 cm (7.9 inches) in females. The body and tail are compressed (taller than wide) while the limbs are long and muscular, each ending at five sharp claws. In both sexes, a fringe of enlarged scales runs down the length of the spine. The tympanum (eardrum) is partially exposed, with its rim covered by scales. There is a row of 8 or 9 large white plate-like scales on the edge of the lower jaw, below the infralabials (the scale row of the lower lip).
Chinese water dragons show distinct sexual dimorphism; the males are heavier (up to 0.6 kg or 1.3 lbs) and have prominent display features. An arched crest extends along the rear of the neck onto the back, and another low crest is present at the base of the tail. The head is larger and more triangular, while the cheeks are swollen into jowls with pale tubercles (prominent pointed scales). There is no dewlap, unlike anoles and iguanas. Males have a functional series of femoral pores on the underside of the thigh, while in females these pores are little more than subtle indentations. Females reach a maximum weight 0.25 kg (0.55 lb), with a smaller head and lower crests.
Coloration is usually a shade of bright green, though they can take on a brown or grey hue when stressed. In juveniles, the body has vibrant green or turquoise diagonal stripes, which may fade with maturity. Most of the tail is ornamented with thick bands of alternating light green and dark brown. In some individuals a dark stripe stretches between the eye and the ear. In most areas the undersides are pale in color, but the throat takes on a more colorful shade of yellow or orange, especially in adult males. Scales on the cheek and lower jaw may acquire a blue or pink coloration in adults.
Distribution | Chinese water dragon | Wikipedia | 462 | 2991134 | https://en.wikipedia.org/wiki/Chinese%20water%20dragon | Biology and health sciences | Iguania | Animals |
Native range
Chinese water dragons are native to the subtropical forests of southern China (Guangdong, Guangxi, and Yunnan provinces) and Southeast Asia (Vietnam, Laos, portions of Cambodia, eastern Thailand). There are also unconfirmed reports from Myanmar.
Introduced populations
An introduced population of Chinese water dragons have established themselves in Hong Kong, probably from released pet animals. The first reports came from Tsing Yi Island in 2004, though the Hong Kong population likely originated from several releases. Since 2010, another breeding population has been established in New Taipei City, Taiwan. Hundreds of the lizards were culled from 2013 to 2017 over concerns about their impact on native Taiwanese wildlife. Introduced individuals (but not breeding populations) have also been reported from Malaysia and Florida.
Habitat
Chinese water dragons are most commonly found within dense closed evergreen forest along the banks of freshwater streams. They live in a humid climate with mild seasons: average humidity levels of 40–80% and temperatures ranging from 80–90 °F (26–32 °C). Their reliance on undisturbed forest streams indicates that, despite their wide extent of occurrence in southeast Asia, Chinese water dragons are a geographically restricted species. They can be found between elevations of around 50 meters (164 ft) and 820 meters (2690 ft), though their density and abundance decline strongly above around 270 meters (885 ft).
Despite their preference for undisturbed habitat, Chinese water dragons are common in the urban parks of Hong Kong. Nevertheless, they show a systematic preference for areas with streamside boulders, taller trees, and a denser canopy. Though all sampled individuals have streams within their territory, less than half of first-hand recordings occur within close proximity (< 5 meters) to a stream. Males prefer to defend wide or deep streams while female territories occupy more dry land. Rocks and concrete structures are frequented for basking spots. Orchards are avoided, since they offer no benefits for protection (relative to dense forests) or heat retention (relative to concrete).
Behavior and ecology
Chinese water dragons are diurnal (active during the day) and forage for prey within small territories in the morning and midday. They are also semi-arboreal (spending much of their time in trees or plants). Adult males in particular tend to rest during the night on tree limbs overlooking streams. If threatened, a Chinese water dragon will leap or run to the nearest stream and either swim to safety or remain submerged for up to 90 minutes. | Chinese water dragon | Wikipedia | 496 | 2991134 | https://en.wikipedia.org/wiki/Chinese%20water%20dragon | Biology and health sciences | Iguania | Animals |
In Hong Kong, the average territory size is about 1800 m2, with a small daily range of about 5 meters on average. Male territories generally do not overlap with each other, arguing that males are much more territorial than females. Movement and range patterns appear to be similar between the hot and wet summer and the relatively cool and dry winter, unlike most other subtropical reptiles. This may be an unintentional artefact of the fact that Hong Kong's dry season during the study interval (2015–2016) was unusually warm and wet. Captive male water dragons are very aggressive towards each other while females and juveniles are more tolerant.
Diet
Chinese water dragons are omnivorous and will readily supplement their diet with non-toxic vegetables or fruits in captivity. Nevertheless, their diet consists mainly of insects with occasional small vertebrates, eggs, and snails. Introduced Chinese water dragons in Taiwan are known to prey on native lizards, frogs, snakes, and mice.
According to a 2018 survey in Central Vietnam, Chinese water dragons persist on a diverse variety of terrestrial invertebrates. Termites, ants, orthopterans (grasshoppers and crickets), earthworms, and spiders all make up a significant portion of the diet, along with insect larvae, snails, and various other prey items. Plant material was eaten very rarely by the subjects of this study, though other accounts testify that plants make up a significant portion of the diet in the wild.
Reproduction and life history
Chinese water dragons are oviparous, with a clutch of 5 to 16 eggs buried in sandy riverbanks near the end of the dry winter. The eggs hatch two or three months later in the early part of the wet summer. Maturity is met within the first year, and the generation length is about 6 years. Captive females may breed several times per year. Healthy captive Chinese water dragons have a life expectancy of 10 to 15 years, though some can exceed 20 years of age. | Chinese water dragon | Wikipedia | 393 | 2991134 | https://en.wikipedia.org/wiki/Chinese%20water%20dragon | Biology and health sciences | Iguania | Animals |
Though they reproduce sexually in the wild, there is one reported case of facultative parthenogenesis in a captive individual. A female housed at the Smithsonian National Zoo produced viable offspring in 2016 and 2018, along with numerous unfertilized and nonviable eggs. The two surviving offspring are homozygous or hemizygous at seven particular microsatellite loci in the genome. This condition would be nearly impossible if sexual reproduction was involved, since at least a few of the seven microsatellite loci would be expected to be heterozygous. Physignathus cocincinus is the only agamid known to reproduce via parthenogenesis, though the low hatch rate suggests that this is an accidental occurrence rather than an ingrained evolutionary strategy.
Threats and conservation
Though locally abundant in some areas, the Chinese water dragon faces persistent unrestrained threats and a steadily declining wild population. It is listed as Vulnerable in Vietnamese conservation lists, and Endangered in Thailand and China. On an international scale, the IUCN has rated it as a Vulnerable species since 2017. In accordance with a 2022 proposal, the Chinese water dragon has been listed on CITES Appendix II (requiring a CITES-approved permit for export) since 2023.
Population dynamics
At one site in Cambodia the species experienced a 50% population decline in 18 years, while a 2007 estimate considered the entire Vietnamese population to have declined by 20% over the previous decade. Based on these estimates, the species as a whole may be declining by 30% every 18 years.
A 2017 population survey in Thua Thien Hue Province, Vietnam estimated that up to 250 individuals in total were present at the 11 sampled sites (combined). This is far below the several thousand expected to sustain long-term genetic diversity for a species restrained to narrow riparian habitats. Sites sampled in June 2017 show a slightly lower population and a higher relative proportion of females and sub-adults relative to the same sites in April 2017. Adults were uncommon in both months while juveniles were most common in April, maturing into a large sub-adult cohort by June. Chinese water dragons in Thua Thien Hue occur at moderate to high densities, up to 2.6 per 100 meters in April 2017. | Chinese water dragon | Wikipedia | 460 | 2991134 | https://en.wikipedia.org/wiki/Chinese%20water%20dragon | Biology and health sciences | Iguania | Animals |
Somewhat different patterns were observed in a 2014–2016 survey in Northern Vietnam. In disturbed areas, Chinese water dragons occur at very low densities (as low as 0.17 per 100 meters in 2015), and adults make up to a third of the population. Several previously reported populations were probably extirpated, as individuals could not be found at 8 of the 15 investigated stream transects. Introduced populations in Hong Kong have a much higher population density (about 114 per 100 meters) than native Vietnamese populations.
Hunting and the pet trade
The most severe threat to the species is harvesting for meat and the pet trade. According to a series of 2016 interviews with 21 rural hunter groups, water dragons are a frequent and easy target of traps and hand collecting throughout Thua Thien Hue. Hunting pressure is greatest in May and June, with adult males prioritized due to their large size and conspicuous appearance. This agrees with the decreasing proportion of adult males found in June compared to April. Water dragon meat is typically sold to local restaurants, while eggs are stored in rice wine to be used as traditional medicine. Skins and leather are also traded and exported.
Wild water dragons are captured and sold as pets on social media platforms for both Vietnamese customers and the international markets of Europe and the United States. In Vietnam, about five times as many Chinese water dragons are sold for meat compared to those sold as pets. Exports to Europe began in 1975 and have accelerated in recent decades. From 2010 to 2018, a stable average of around 7,000 live Chinese water dragons per year were exported to the European Union. Approximately 89% came from Vietnam, though information on their production (wild caught or captive bred) is available for fewer than 13% of recorded exports to Europe.
Exports to the United States are even higher despite recent declines: an average of 81,000 per year from 2002 to 2011, and around 48,000 per year from 2013 to 2017. Practically all water dragons exported to the United States are Vietnamese in origin. At least 95% are wild caught while around 3% are reportedly captive bred in Vietnam. It is probable that some individuals sourced from Vietnam were actually collected from other nations, simply using the ports of Vietnam as a transit hub. Captive breeding is a viable but limited conservation strategy; Chinese water dragons breed readily in captivity, though not at a high enough rate to counteract demand. There is no direct evidence that captive breeding programs in Vietnam are in operation, despite claims of captive-bred exports. | Chinese water dragon | Wikipedia | 501 | 2991134 | https://en.wikipedia.org/wiki/Chinese%20water%20dragon | Biology and health sciences | Iguania | Animals |
Habitat loss
A smaller threat, though still impactful, is degradation or removal of the forested stream habitats which water dragons rely on. In Thua Thien Hue, illegal logging and a major highway construction project are likely partially responsible for losses in the Nam Dong and A Luoi districts. These pressures are less prevalent in the uplands of Phong Dien district, which seems to not experience the same degree of population decline. Logging and expansion of agricultural and tourism infrastructure also contribute to the paucity of suitable habitats in Northern Vietnam. Coal mining, stream pollution, and climate change may also threaten the species, as reported for ecologically similar reptiles in the region, such as the Chinese crocodile lizard (Shinisaurus crocodilurus).
Despite its common name, the Chinese water dragon is exceedingly rare in China, where it is threatened by dam construction on top of the same pressures as the Vietnamese populations. Suitably undeveloped habitats are uncommon in Cambodia and Laos. The few Chinese water dragons present in Thailand are stable and locally abundant thanks to their range lining up with protected areas such as Khao Yai National Park and Namtok Phlio National Park.
Gallery
Wild individuals
Captive individuals | Chinese water dragon | Wikipedia | 238 | 2991134 | https://en.wikipedia.org/wiki/Chinese%20water%20dragon | Biology and health sciences | Iguania | Animals |
Relative dating is the science of determining the relative order of past events (i.e., the age of an object in comparison to another), without necessarily determining their absolute age (i.e., estimated age). In geology, rock or superficial deposits, fossils and lithologies can be used to correlate one stratigraphic column with another. Prior to the discovery of radiometric dating in the early 20th century, which provided a means of absolute dating, archaeologists and geologists used relative dating to determine ages of materials. Though relative dating can only determine the sequential order in which a series of events occurred, not when they occurred, it remains a useful technique. Relative dating by biostratigraphy is the preferred method in paleontology and is, in some respects, more accurate. The Law of Superposition, which states that older layers will be deeper in a site than more recent layers, was the summary outcome of 'relative dating' as observed in geology from the 17th century to the early 20th century.
Geology
The regular order of the occurrence of fossils in rock layers was discovered around 1800 by William Smith. While digging the Somerset Coal Canal in southwest England, he found that fossils were always in the same order in the rock layers. As he continued his job as a surveyor, he found the same patterns across England. He also found that certain animals were in only certain layers and that they were in the same layers all across England. Due to that discovery, Smith was able to recognize the order that the rocks were formed. Sixteen years after his discovery, he published a geological map of England showing the rocks of different geologic time eras.
Principles of relative dating
Methods for relative dating were developed when geology first emerged as a natural science in the 18th century. Geologists still use the following principles today as a means to provide information about geologic history and the timing of geologic events.
Uniformitarianism
The principle of Uniformitarianism states that the geologic processes observed in operation that modify the Earth's crust at present have worked in much the same way over geologic time. A fundamental principle of geology advanced by the 18th century Scottish physician and geologist James Hutton, is that "the present is the key to the past." In Hutton's words: "the past history of our globe must be explained by what can be seen to be happening now." | Relative dating | Wikipedia | 475 | 2992637 | https://en.wikipedia.org/wiki/Relative%20dating | Physical sciences | Geochronology | Earth science |
Intrusive relationships
The principle of intrusive relationships concerns crosscutting intrusions. In geology, when an igneous intrusion cuts across a formation of sedimentary rock, it can be determined that the igneous intrusion is younger than the sedimentary rock. There are a number of different types of intrusions, including stocks, laccoliths, batholiths, sills and dikes.
Cross-cutting relationships
The principle of cross-cutting relationships pertains to the formation of faults and the age of the sequences through which they cut. Faults are younger than the rocks they cut; accordingly, if a fault is found that penetrates some formations but not those on top of it, then the formations that were cut are older than the fault, and the ones that are not cut must be younger than the fault. Finding the key bed in these situations may help determine whether the fault is a normal fault or a thrust fault.
Inclusions and components
The principle of inclusions and components explains that, with sedimentary rocks, if inclusions (or clasts) are found in a formation, then the inclusions must be older than the formation that contains them. For example, in sedimentary rocks, it is common for gravel from an older formation to be ripped up and included in a newer layer. A similar situation with igneous rocks occurs when xenoliths are found. These foreign bodies are picked up as magma or lava flows, and are incorporated, later to cool in the matrix. As a result, xenoliths are older than the rock which contains them.
Original horizontality
The principle of original horizontality states that the deposition of sediments occurs as essentially horizontal beds. Observation of modern marine and non-marine sediments in a wide variety of environments supports this generalization (although cross-bedding is inclined, the overall orientation of cross-bedded units is horizontal). | Relative dating | Wikipedia | 378 | 2992637 | https://en.wikipedia.org/wiki/Relative%20dating | Physical sciences | Geochronology | Earth science |
Superposition
The law of superposition states that a sedimentary rock layer in a tectonically undisturbed sequence is younger than the one beneath it and older than the one above it. This is because it is not possible for a younger layer to slip beneath a layer previously deposited. The only disturbance that the layers experience is bioturbation, in which animals and/or plants move things in the layers. however, this process is not enough to allow the layers to change their positions. This principle allows sedimentary layers to be viewed as a form of vertical time line, a partial or complete record of the time elapsed from deposition of the lowest layer to deposition of the highest bed.
Faunal succession
The principle of faunal succession is based on the appearance of fossils in sedimentary rocks. As organisms exist at the same time period throughout the world, their presence or (sometimes) absence may be used to provide a relative age of the formations in which they are found. Based on principles laid out by William Smith almost a hundred years before the publication of Charles Darwin's theory of evolution, the principles of succession were developed independently of evolutionary thought. The principle becomes quite complex, however, given the uncertainties of fossilization, the localization of fossil types due to lateral changes in habitat (facies change in sedimentary strata), and that not all fossils may be found globally at the same time.
Lateral continuity
The principle of lateral continuity states that layers of sediment initially extend laterally in all directions; in other words, they are laterally continuous. As a result, rocks that are otherwise similar, but are now separated by a valley or other erosional feature, can be assumed to be originally continuous.
Layers of sediment do not extend indefinitely; rather, the limits can be recognized and are controlled by the amount and type of sediment available and the size and shape of the sedimentary basin. Sediment will continue to be transported to an area and it will eventually be deposited. However, the layer of that material will become thinner as the amount of material lessens away from the source.
Often, coarser-grained material can no longer be transported to an area because the transporting medium has insufficient energy to carry it to that location. In its place, the particles that settle from the transporting medium will be finer-grained, and there will be a lateral transition from coarser- to finer-grained material. The lateral variation in sediment within a stratum is known as sedimentary facies. | Relative dating | Wikipedia | 498 | 2992637 | https://en.wikipedia.org/wiki/Relative%20dating | Physical sciences | Geochronology | Earth science |
If sufficient sedimentary material is available, it will be deposited up to the limits of the sedimentary basin. Often, the sedimentary basin is within rocks that are very different from the sediments that are being deposited, in which the lateral limits of the sedimentary layer will be marked by an abrupt change in rock type.
Inclusions of igneous rocks
Melt inclusions are small parcels or "blobs" of molten rock that are trapped within crystals that grow in the magmas that form igneous rocks. In many respects they are analogous to fluid inclusions. Melt inclusions are generally small – most are less than 100 micrometres across (a micrometre is one thousandth of a millimeter, or about 0.00004 inches). Nevertheless, they can provide an abundance of useful information. Using microscopic observations and a range of chemical microanalysis techniques geochemists and igneous petrologists can obtain a range of useful information from melt inclusions. Two of the most common uses of melt inclusions are to study the compositions of magmas present early in the history of specific magma systems. This is because inclusions can act like "fossils" – trapping and preserving these early melts before they are modified by later igneous processes. In addition, because they are trapped at high pressures many melt inclusions also provide important information about the contents of volatile elements (such as H2O, CO2, S and Cl) that drive explosive volcanic eruptions.
Sorby (1858) was the first to document microscopic melt inclusions in crystals. The study of melt inclusions has been driven more recently by the development of sophisticated chemical analysis techniques. Scientists from the former Soviet Union lead the study of melt inclusions in the decades after World War II (Sobolev and Kostyuk, 1975), and developed methods for heating melt inclusions under a microscope, so changes could be directly observed.
Although they are small, melt inclusions may contain a number of different constituents, including glass (which represents magma that has been quenched by rapid cooling), small crystals and a separate vapour-rich bubble. They occur in most of the crystals found in igneous rocks and are common in the minerals quartz, feldspar, olivine and pyroxene. The formation of melt inclusions appears to be a normal part of the crystallization of minerals within magmas, and they can be found in both volcanic and plutonic rocks. | Relative dating | Wikipedia | 493 | 2992637 | https://en.wikipedia.org/wiki/Relative%20dating | Physical sciences | Geochronology | Earth science |
Included fragments
The law of included fragments is a method of relative dating in geology. Essentially, this law states that clasts in a rock are older than the rock itself. One example of this is a xenolith, which is a fragment of country rock that fell into passing magma as a result of stoping. Another example is a derived fossil, which is a fossil that has been eroded from an older bed and redeposited into a younger one.
This is a restatement of Charles Lyell's original principle of inclusions and components from his 1830 to 1833 multi-volume Principles of Geology, which states that, with sedimentary rocks, if inclusions (or clasts) are found in a formation, then the inclusions must be older than the formation that contains them. For example, in sedimentary rocks, it is common for gravel from an older formation to be ripped up and included in a newer layer. A similar situation with igneous rocks occurs when xenoliths are found. These foreign bodies are picked up as magma or lava flows and are incorporated later to cool in the matrix. As a result, xenoliths are older than the rock which contains them.
Planetology
Relative dating is used to determine the order of events on Solar System objects other than Earth; for decades, planetary scientists have used it to decipher the development of bodies in the Solar System, particularly in the vast majority of cases for which we have no surface samples. Many of the same principles are applied. For example, if a valley is formed inside an impact crater, the valley must be younger than the crater.
Craters are very useful in relative dating; as a general rule, the younger a planetary surface is, the fewer craters it has. If long-term cratering rates are known to enough precision, crude absolute dates can be applied based on craters alone; however, cratering rates outside the Earth-Moon system are poorly known.
Archaeology
Relative dating methods in archaeology are similar to some of those applied in geology. The principles of typology can be compared to the biostratigraphic approach in geology. | Relative dating | Wikipedia | 430 | 2992637 | https://en.wikipedia.org/wiki/Relative%20dating | Physical sciences | Geochronology | Earth science |
Belostomatidae is a family of freshwater hemipteran insects known as giant water bugs or colloquially as toe-biters, Indian toe-biters, electric-light bugs (because they fly to lights in large numbers), alligator ticks, or alligator fleas (in Florida). They are the largest insects in the order Hemiptera. There are about 170 species found in freshwater habitats worldwide, with more than 110 in the Neotropics, more than 20 in Africa, almost as many in the Nearctic, and far fewer elsewhere. These predators are typically encountered in freshwater ponds, marshes and slow-flowing streams. Most species are at least long, although smaller species, down to , also exist. The largest are members of the genus Lethocerus, which can exceed and nearly reach the length of some of the largest beetles in the world. Giant water bugs are a popular food in parts of Asia.
The oldest fossil member of this family is Triassonepa from the Late Triassic-aged Cow Branch Formation of Virginia & North Carolina, USA.
Morphology
Belostomatids have a flattened, obovoid to ovoid-elongate body, and usually the legs are flattened. The head features two large compound eyes, but lacks ocelli, contrasting with many hemipterans. Short antennae are tucked in grooves behind the eyes. A short breathing tube can be retracted into its abdomen. Adults cannot breathe under water, so must periodically place the breathing tube at the surface for air (similar to a snorkel).
Their hind tarsi have two apical claws. The frontal legs are modified into raptorial appendages that they use to grab their prey, except in the African Limnogeton, which has "normal" forelegs and is a specialized snail-eater. Once caught, the prey are stabbed with their proboscis and a powerful proteolytic saliva is injected, allowing the Belostomatid to suck out the liquefied remains. Wing pads can be seen from the dorsal view. While the members of the subfamily Lethocerinae can disperse by flying, other species, including Abedus herberti, have a greatly reduced flight apparatus and are flightless. Giant Water Bugs exhibit muscle regression as they develop from nymphs to adults, adapting their musculature for a more energy-efficient predatory lifestyle, which may influence their hunting strategies and ecological interactions. | Belostomatidae | Wikipedia | 497 | 2996328 | https://en.wikipedia.org/wiki/Belostomatidae | Biology and health sciences | Hemiptera (true bugs) | Animals |
Subfamilies and genera
BioLib lists three extant subfamilies and a number of fossil taxa:
Belostomatinae
Auth. Leach, 1815
Abedus Stål, 1862
Appasus Amyot & Serville, 1843
Belostoma Latreille, 1807
Diplonychus Laporte de Castelnau, 1833 (synonym Sphaerodema Laporte, 1833)
Hydrocyrius Spinola, 1850 (synonym Poissonia Brown, 1948)
Limnogeton Mayr, 1853
Weberiella De Carlo, 1966
Fossil genera
Horvathiniinae
Auth. Lauck & Menke, 1961; South America
Horvathinia Montandon, 1911
Lethocerinae
Auth. Lauck & Menke, 1961
Benacus Stål, 1861
Kirkaldyia Montandon, 1909
Lethocerus Mayr, 1853
Fossil taxa
subfamily Stygeonepinae Popov, 1971 †
Aenictobelostoma Polhemus, 2000 †
Belostomates Schöberlin, 1888 †
Lethopterus Popov, 1989 †
Manocerus Zhang, 1989 †
Scarabaeides Germar, 1839 †
Triassonepa Criscione & Grimaldi, 2017 †
Habits
Feeding and defense
Belostomatids are aggressive predators that stalk, capture, and feed on fish, amphibians, as well as aquatic invertebrates such as snails and crustaceans. The largest species have also been found to capture and feed on baby turtles and water snakes. They often lie motionless at the bottom of a body of water, attached to various objects, where they wait for prey to come near. They then strike, injecting a venomous digestive saliva with their rostrum. Although their sting is excruciatingly painful, it is of no medical significance. Occasionally, when encountered by a larger animal or a human, they have been known to "play dead" and most species can emit a fluid from their anus. Due to this, they are assumed dead by humans only to later "come alive" with painful results.
Breeding | Belostomatidae | Wikipedia | 434 | 2996328 | https://en.wikipedia.org/wiki/Belostomatidae | Biology and health sciences | Hemiptera (true bugs) | Animals |
Belostomatids show paternal care and these aspects have been studied extensively, among others involving the North American Belostoma flumineum and the East Asian Lethocerus (Kirkaldyia) deyrollei. In species of the subfamily Belostomatinae, the eggs are typically laid on the male's wings and carried until they hatch. The male cannot mate during this period. The males invest considerable time and energy in reproduction and females take the role of actively finding males to mate. This role reversal matches the predictions of R. L. Trivers' parental investment theory. In the subfamily Lethocerinae, the eggs are laid on emergent vegetation and guarded by the male.
In Asian cuisine
Belostomatids can be found for sale in markets mainly in Southeast Asia involving the species Lethocerus indicus. In Southeast Asia they are often collected for this purpose using large floating traps on ponds, set with black lights to attract the bugs. Adults fly at night, like many aquatic insects, and are attracted to lights during the breeding season. | Belostomatidae | Wikipedia | 219 | 2996328 | https://en.wikipedia.org/wiki/Belostomatidae | Biology and health sciences | Hemiptera (true bugs) | Animals |
Antiparasitics are a class of medications which are indicated for the treatment of parasitic diseases, such as those caused by helminths, amoeba, ectoparasites, parasitic fungi, and protozoa, among others. Antiparasitics target the parasitic agents of the infections by destroying them or inhibiting their growth; they are usually effective against a limited number of parasites within a particular class. Antiparasitics are one of the antimicrobial drugs which include antibiotics that target bacteria, and antifungals that target fungi. They may be administered orally, intravenously or topically. Overuse or misuse of antiparasitics can lead to the development of antimicrobial resistance.
Broad-spectrum antiparasitics, analogous to broad-spectrum antibiotics for bacteria, are antiparasitic drugs with efficacy in treating a wide range of parasitic infections caused by parasites from different classes.
Types
Broad-spectrum
Nitazoxanide
Antiprotozoals
Melarsoprol (for treatment of sleeping sickness caused by Trypanosoma brucei)
Eflornithine (for sleeping sickness)
Metronidazole (for vaginitis caused by Trichomonas)
Tinidazole (for intestinal infections caused by Giardia lamblia)
Miltefosine (for the treatment of visceral and cutaneous leishmaniasis, currently undergoing investigation for Chagas disease)
Antihelminthic
Antinematodes
Mebendazole (for most nematode infections)
Pyrantel pamoate (for most nematode infections)
Thiabendazole (for roundworm infections)
Diethylcarbamazine (for treatment of Lymphatic filariasis)
Ivermectin (for prevention of river blindness)
Fenbendazole
Anticestodes
Niclosamide (for tapeworm infections)
Praziquantel (for tapeworm infections)
Albendazole (broad spectrum)
Antitrematodes
[Praziquantel]
Antiamoebics
Rifampin
Amphotericin B
Antifungals
Fumagillin (for microsporidiosis)
Medical uses
Antiparasitics treat parasitic diseases, which impact an estimated 2 billion people.
Administration
Antiparastics may be given via a variety of routes depending on the specific medication, including oral, topical, and intravenous. | Antiparasitic | Wikipedia | 501 | 7143953 | https://en.wikipedia.org/wiki/Antiparasitic | Biology and health sciences | Antiparasitic | Health |
Resistance to antiparasitics has been a growing concern, especially in veterinary medicine. The Egg hatch assay can be used to determine whether a parasite causing an infection has become resistant to standard drug treatments.
Drug development history
Early antiparasitics were ineffective, frequently toxic to patients, and difficult to administer due to the difficulty in distinguishing between the host and the parasite.
Between 1975 and 1999 only 13 of 1,300 new drugs were antiparasitics, which raised concerns that insufficient incentives existed to drive development of new treatments for diseases that disproportionately target low-income countries. This led to new public sector and public-private partnerships (PPPs), including investment by the Bill and Melinda Gates Foundation. Between 2000 and 2005, twenty new antiparasitic agents were developed or in development. Metal-containing compounds are the subject of another avenue of approach.
Research
In the last decades, triazolopyrimidines and their metal complexes have been looked at as an alternative drug to the existing commercial antimonials, searching for a decrease in side effects and the development of parasite drug resistance. | Antiparasitic | Wikipedia | 225 | 7143953 | https://en.wikipedia.org/wiki/Antiparasitic | Biology and health sciences | Antiparasitic | Health |
A regular dodecahedron or pentagonal dodecahedron is a dodecahedron composed of regular pentagonal faces, three meeting at each vertex. It is an example of Platonic solids, described as cosmic stellation by Plato in his dialogues, and it was used as part of Solar System proposed by Johannes Kepler. However, the regular dodecahedron, including the other Platonic solids, has already been described by other philosophers since antiquity.
The regular dodecahedron is the family of truncated trapezohedron because it is the result of truncating axial vertices of a pentagonal trapezohedron. It is also a Goldberg polyhedron because it is the initial polyhedron to construct new polyhedrons by the process of chamfering. It has a relation with other Platonic solids, one of them is the regular icosahedron as its dual polyhedron. Other new polyhedrons can be constructed by using regular dodecahedron.
The regular dodecahedron's metric properties and construction are associated with the golden ratio. The regular dodecahedron can be found in many popular cultures: Roman dodecahedron, the children's story, toys, and painting arts. It can also be found in nature and supramolecules, as well as the shape of the universe. The skeleton of a regular dodecahedron can be represented as the graph called the dodecahedral graph, a Platonic graph. Its property of the Hamiltonian, a path visits all of its vertices exactly once, can be found in a toy called icosian game.
As a Platonic solid | Regular dodecahedron | Wikipedia | 325 | 7149361 | https://en.wikipedia.org/wiki/Regular%20dodecahedron | Mathematics | Three-dimensional space | null |
The regular dodecahedron is a polyhedron with twelve pentagonal faces, thirty edges, and twenty vertices. It is one of the Platonic solids, a set of polyhedrons in which the faces are regular polygons that are congruent and the same number of faces meet at a vertex. This set of polyhedrons is named after Plato. In Theaetetus, a dialogue of Plato, Plato hypothesized that the classical elements were made of the five uniform regular solids. Plato described the regular dodecahedron, obscurely remarked, "...the god used [it] for arranging the constellations on the whole heaven". Timaeus, as a personage of Plato's dialogue, associates the other four Platonic solids—regular tetrahedron, cube, regular octahedron, and regular icosahedron—with the four classical elements, adding that there is a fifth solid pattern which, though commonly associated with the regular dodecahedron, is never directly mentioned as such; "this God used in the delineation of the universe." Aristotle also postulated that the heavens were made of a fifth element, which he called aithêr (aether in Latin, ether in American English).
Following its attribution with nature by Plato, Johannes Kepler in his Harmonices Mundi sketched each of the Platonic solids, one of them is a regular dodecahedron. In his Mysterium Cosmographicum, Kepler also proposed the Solar System by using the Platonic solids setting into another one and separating them with six spheres resembling the six planets. The ordered solids started from the innermost to the outermost: regular octahedron, regular icosahedron, regular dodecahedron, regular tetrahedron, and cube. | Regular dodecahedron | Wikipedia | 366 | 7149361 | https://en.wikipedia.org/wiki/Regular%20dodecahedron | Mathematics | Three-dimensional space | null |
Many antiquity philosophers described the regular dodecahedron, including the rest of the Platonic solids. Theaetetus gave a mathematical description of all five and may have been responsible for the first known proof that no other convex regular polyhedra exist. Euclid completely mathematically described the Platonic solids in the Elements, the last book (Book XIII) of which is devoted to their properties. Propositions 13–17 in Book XIII describe the construction of the tetrahedron, octahedron, cube, icosahedron, and dodecahedron in that order. For each solid, Euclid finds the ratio of the diameter of the circumscribed sphere to the edge length. In Proposition 18 he argues that there are no further convex regular polyhedra. Iamblichus states that Hippasus, a Pythagorean, perished in the sea, because he boasted that he first divulged "the sphere with the twelve pentagons".
Relation to the regular icosahedron
The dual polyhedron of a dodecahedron is the regular icosahedron. One property of the dual polyhedron generally is that the original polyhedron and its dual share the same three-dimensional symmetry group. In the case of the regular dodecahedron, it has the same symmetry as the regular icosahedron, the icosahedral symmetry . The regular dodecahedron has ten three-fold axes passing through pairs of opposite vertices, six five-fold axes passing through the opposite faces centers, and fifteen two-fold axes passing through the opposite sides midpoints.
When a regular dodecahedron is inscribed in a sphere, it occupies more of the sphere's volume (66.49%) than an icosahedron inscribed in the same sphere (60.55%). The resulting of both spheres' volumes initially began from the problem by ancient Greeks, determining which of two shapes has a larger volume: an icosahedron inscribed in a sphere, or a dodecahedron inscribed in the same sphere. The problem was solved by Hero of Alexandria, Pappus of Alexandria, and Fibonacci, among others. Apollonius of Perga discovered the curious result that the ratio of volumes of these two shapes is the same as the ratio of their surface areas. Both volumes have formulas involving the golden ratio but are taken to different powers. | Regular dodecahedron | Wikipedia | 480 | 7149361 | https://en.wikipedia.org/wiki/Regular%20dodecahedron | Mathematics | Three-dimensional space | null |
Golden rectangle may also related to both regular icosahedron and regular dodecahedron. The regular icosahedron can be constructed by intersecting three golden rectangles perpendicularly, arranged in two-by-two orthogonal, and connecting each of the golden rectangle's vertices with a segment line. There are 12 regular icosahedron vertices, considered as the center of 12 regular dodecahedron faces.
Relation to the regular tetrahedron
As two opposing tetrahedra can be inscribed in a cube, and five cubes can be inscribed in a dodecahedron, ten tetrahedra in five cubes can be inscribed in a dodecahedron: two opposing sets of five, with each set covering all 20 vertices and each vertex in two tetrahedra (one from each set, but not the opposing pair). As quoted by ,
Configuration matrix
The configuration matrix is a matrix in which the rows and columns correspond to the elements of a polyhedron as in the vertices, edges, and faces. The diagonal of a matrix denotes the number of each element that appears in a polyhedron, whereas the non-diagonal of a matrix denotes the number of the column's elements that occur in or at the row's element. The regular dodecahedron can be represented in the following matrix:
Relation to the golden ratio
The golden ratio is the ratio between two numbers equal to the ratio of their sum to the larger of the two quantities. It is one of two roots of a polynomial, expressed as . The golden ratio can be applied to the regular dodecahedron's metric properties, as well as to construct the regular dodecahedron.
The surface area and the volume of a regular dodecahedron of edge length are:
The following Cartesian coordinates define the twenty vertices of a regular dodecahedron centered at the origin and suitably scaled and oriented:
If the edge length of a regular dodecahedron is , the radius of a circumscribed sphere (one that touches the regular dodecahedron at all vertices), the radius of an inscribed sphere (tangent to each of the regular dodecahedron's faces), and the midradius (one that touches the middle of each edge) are:
Given a regular dodecahedron of edge length one, is the radius of a circumscribing sphere about a cube of edge length , and is the apothem of a regular pentagon of edge length . | Regular dodecahedron | Wikipedia | 496 | 7149361 | https://en.wikipedia.org/wiki/Regular%20dodecahedron | Mathematics | Three-dimensional space | null |
The dihedral angle of a regular dodecahedron between every two adjacent pentagonal faces is , approximately 116.565°.
Other related geometric objects
The regular dodecahedron can be interpreted as a truncated trapezohedron. It is the set of polyhedrons that can be constructed by truncating the two axial vertices of a trapezohedron. Here, the regular dodecahedron is constructed by truncating the pentagonal trapezohedron.
The regular dodecahedron can be interpreted as the Goldberg polyhedron. It is a set of polyhedrons containing hexagonal and pentagonal faces. Other than two Platonic solids—tetrahedron and cube—the regular dodecahedron is the initial of Goldberg polyhedron construction, and the next polyhedron is resulted by truncating all of its edges, a process called chamfer. This process can be continuously repeated, resulting in more new Goldberg's polyhedrons. These polyhedrons are classified as the first class of a Goldberg polyhedron.
The stellations of the regular dodecahedron make up three of the four Kepler–Poinsot polyhedra. The first stellation of a regular dodecahedron is constructed by attaching its layer with pentagonal pyramids, forming a small stellated dodecahedron. The second stellation is by attaching the small stellated dodecahedron with wedges, forming a great dodecahedron. The third stellation is by attaching the great dodecahedron with the sharp triangular pyramids, forming a great stellated dodecahedron.
Appearances
In visual arts
Regular dodecahedra have been used as dice and probably also as divinatory devices. During the Hellenistic era, small hollow bronze Roman dodecahedra were made and have been found in various Roman ruins in Europe. Its purpose is not certain.
In 20th-century art, dodecahedra appear in the work of M. C. Escher, such as his lithographs Reptiles (1943) and Gravitation (1952). In Salvador Dalí's painting The Sacrament of the Last Supper (1955), the room is a hollow regular dodecahedron. Gerard Caris based his entire artistic oeuvre on the regular dodecahedron and the pentagon, presented as a new art movement coined as Pentagonism. | Regular dodecahedron | Wikipedia | 476 | 7149361 | https://en.wikipedia.org/wiki/Regular%20dodecahedron | Mathematics | Three-dimensional space | null |
In toys and popular culture
In modern role-playing games, the regular dodecahedron is often used as a twelve-sided die, one of the more common polyhedral dice. The Megaminx twisty puzzle is shaped like a regular dodecahedron alongside its larger and smaller order analogues.
In the children's novel The Phantom Tollbooth, the regular dodecahedron appears as a character in the land of Mathematics. Each face of the regular dodecahedron describes the various facial expressions, swiveling to the front as required to match his mood.
In nature and supramolecules
The fossil coccolithophore Braarudosphaera bigelowii (see figure), a unicellular coastal phytoplanktonic alga, has a calcium carbonate shell with a regular dodecahedral structure about 10 micrometers across.
The hydrocarbon dodecahedrane, some quasicrystals and cages have dodecahedral shape (see figure). Some regular crystals such as garnet and diamond are also said to exhibit "dodecahedral" habit, but this statement actually refers to the rhombic dodecahedron shape.
Shape of the universe
Various models have been proposed for the global geometry of the universe. These proposals include the Poincaré dodecahedral space, a positively curved space consisting of a regular dodecahedron whose opposite faces correspond (with a small twist). This was proposed by Jean-Pierre Luminet and colleagues in 2003, and an optimal orientation on the sky for the model was estimated in 2008.
In Bertrand Russell's 1954 short story "The Mathematician's Nightmare: The Vision of Professor Squarepunt", the number 5 said: "I am the number of fingers on a hand. I make pentagons and pentagrams. And but for me dodecahedra could not exist; and, as everyone knows, the universe is a dodecahedron. So, but for me, there could be no universe."
Dodecahedral graph | Regular dodecahedron | Wikipedia | 412 | 7149361 | https://en.wikipedia.org/wiki/Regular%20dodecahedron | Mathematics | Three-dimensional space | null |
According to Steinitz's theorem, the graph can be represented as the skeleton of a polyhedron; roughly speaking, a framework of a polyhedron. Such a graph has two properties. It is planar, meaning the edges of a graph are connected to every vertex without crossing other edges. It is also three-connected graph, meaning that, whenever a graph with more than three vertices, and two of the vertices are removed, the edges remain connected. The skeleton of a regular dodecahedron can be represented as a graph, and it is called the dodecahedral graph, a Platonic graph.
This graph can also be constructed as the generalized Petersen graph , where the vertices of a decagon are connected to those of two pentagons, one pentagon connected to odd vertices of the decagon and the other pentagon connected to the even vertices. Geometrically, this can be visualized as the ten-vertex equatorial belt of the dodecahedron connected to the two 5-vertex polar regions, one on each side.
The high degree of symmetry of the polygon is replicated in the properties of this graph, which are distance-transitive, distance-regular, and symmetric. The automorphism group has order a hundred and twenty. The vertices can be colored with 3 colors, as can the edges, and the diameter is five.
The dodecahedral graph is Hamiltonian, meaning a path visits all of its vertices exactly once. The name of this property is named after William Rowan Hamilton, who invented a mathematical game known as the icosian game. The game's object was to find a Hamiltonian cycle along the edges of a dodecahedron. | Regular dodecahedron | Wikipedia | 337 | 7149361 | https://en.wikipedia.org/wiki/Regular%20dodecahedron | Mathematics | Three-dimensional space | null |
The Thylacocephala (from the Greek or , meaning "pouch", and or meaning "head") are group of extinct probable mandibulate arthropods, that have been considered by some researchers as having possible crustacean affinities. As a class they have a short research history, having been erected in the early 1980s.
They typically possess a large, laterally flattened carapace that encompasses the entire body. The compound eyes tend to be large and bulbous, and occupy a frontal notch on the carapace. They possess three pairs of large raptorial limbs, and the abdomen bears a battery of small swimming limbs. Their size ranges from ~15 mm to potentially up to 250 mm.
Inconclusive claims of thylacocephalans have been reported from the lower lower Cambrian (Zhenghecaris), but later study considered that genus as radiodont or arthropod with uncertain systematic position. The oldest unequivocal fossils are Upper Ordovician and Lower Silurian in age. As a group, the Thylacocephala survived to the Santonian stage of the Upper Cretaceous, around 84 million years ago.
Beyond this, there remains much uncertainty concerning fundamental aspects of the thylacocephalan anatomy, mode of life, and relationship to the Crustacea, with whom they have always been cautiously aligned. | Thylacocephala | Wikipedia | 285 | 7149700 | https://en.wikipedia.org/wiki/Thylacocephala | Biology and health sciences | Fossil arthropods | Animals |
Research history
The Thylacocephala is only recently described as a class, yet species now included within the group were first described at the turn of the century. These were typically assigned to the phyllocarids despite an apparent lack of abdomen and appendages. In 1982/83, three research groups independently created higher taxa to accommodate new species. Based on a specimen from northern Italy, Pinna et al. designated a new class, Thylacocephala, while Secrétan – studying Dollocaris ingens, a species from the La Voulte-sur-Rhône konservat-lagerstätte in France – erected the class Conchyliocarida. Briggs & Rolfe, working on fossils from Australia's Devonian deposits were unable to attribute certain specimens to a known group, and created an order of uncertain affinities, the Concavicarida, to accommodate them. It was apparent the three groups were in fact working on a single major taxon (Rolfe noted disagreements over interpretation and taxonomic placement largely resulted from a disparity of sizes and differences in preservation.) The group took the name Thylacocephala by priority, with Concavicarida and Conchyliocarida subjugated to orders, erected by Rolfe, and modified by Schram.
Taxonomy
Researchers agree the Thylacocephala represent a class. Some efforts have been made at further classification: Schram split currently known taxa into two orders:
Concavicarida Briggs & Rolfe, 1983 which possesses:
A large, well developed optic notch
A discrete compound eye
A fused rostrum
8 to 16 homologous well-demarcated trunk segments diminishing in height anteriorly and posteriorly
Order includes Ainiktozoon (Silurian), Harrycaris (Devonian), Concavicaris (Devonian to Carboniferous), Dollocaris (Jurassic).
Conchyliocarida Secrétan, 1983:
Lacks an optic notch
Eyes on a protruding sac-like cephalon
No rostrum.
Order includes Convexicaris (Carboniferous), Yangzicaris (Triassic), and Atropicaris, Austriocaris, Clausocaris, Kilianocaris, Ostenocaris, and Paraostenia from the Jurassic. | Thylacocephala | Wikipedia | 479 | 7149700 | https://en.wikipedia.org/wiki/Thylacocephala | Biology and health sciences | Fossil arthropods | Animals |
The accuracy of this scheme has been questioned in recent papers, as it stresses differences in the eyes and exoskeletal structure, which – in modern arthropods – tend to be a response to environmental conditions. Thus it has been suggested these features are too strongly controlled by external factors to be used alone to distinguish higher taxa. The problem is exacerbated by the limited number of thylacocephalan species known. More reliable anatomical indicators would include segmentation and appendage attachments (requiring the internal anatomy, currently elusive as a result of the carapace).
Genera
Class: Thylacocephala
Ainiktozoon
Ankitokazocaris
Eodollocaris
Falcatacaris
Ligulacaris
Paraostenia
Polzia
Rugocaris
Silesicaris
Thylacares
Victoriacaris
Order Concavicarida
Family Austriocarididae
Austriocaris
Yangzicaris
Family Clausocarididae
Clausocaris
Convexicaris
Family Concavicarididae
Concavicaris
Harrycaris
Paraconcavicaris
Family: Microcarididae
Atropicaris
Ferrecaris
Keelicaris
Microcaris
Thylacocephalus
Family: Protozoeidae
Globulocaris
Hamaticaris
Protozoea
Pseuderichthus
Order Conchyliocarida
Family: Dollocarididae
Dollocaris
Mayrocaris
Paradollocaris
Thylacocaris
Family: Ostenocarididae
Kilianocaris
Ostenocaris
Anatomy | Thylacocephala | Wikipedia | 316 | 7149700 | https://en.wikipedia.org/wiki/Thylacocephala | Biology and health sciences | Fossil arthropods | Animals |
Based on Vannier, modified after Schram:
The Thylacocephala are bivalved arthropods with morphology exemplified by three pairs of long raptorial (predatory) appendages and hypertrophied eyes. They have a worldwide distribution. A laterally compressed, shield−like carapace encloses the entire body, and often has an anterior rostrum−notch complex and posterior rostrum. Its lateral surface can be externally ornamented, and evenly convex or with longitudinal ridges. Spherical or drop-shaped eyes are situated in the optic notches, and are often hypertrophied, filling the notches or forming a paired, frontal globular structure. No prominent abdominal features emerge from the carapace, and the cephalon is obscured. Even so, some authors have suggested the presence of five cephalic appendages, three of which could be the very long genticulate and chelate raptorials protruding beyond the ventral margin. Alternatively these could originate from three anterior trunk segments. The posterior trunk has a series of eight to twenty styliform, filamentous pleopod-like appendages, decreasing in size posteriorly. Most Thylacocephala have eight pairs of well developed gills, found in the trunk region.
Beyond this there is a lack of knowledge about even basic thylacocephalan anatomy, including the number of posterior segments, origin of the raptorials, number of cephalic appendages, shape and attachment of gills, character of mouth, stomach and gut. This results from the class's all–encompassing carapace, which prevents the study of their internal anatomy in fossils.
Affinities
It is universally accepted that the Thylacocephala are arthropods, yet the position within this phylum is debated. It had formerly been cautiously assumed that the class was a member of the Crustacea, but no conclusive proof exists. The strongest apomorphy aligning the class with other crustaceans is the carapace. As this feature has evolved independently numerous times within the Crustacea and other arthropods, it is not a very reliable pointer, and such evidence alone remains insufficient to align the class with the crustaceans. | Thylacocephala | Wikipedia | 470 | 7149700 | https://en.wikipedia.org/wiki/Thylacocephala | Biology and health sciences | Fossil arthropods | Animals |
Of the features which could prove crustacean affinities, the arrangement of mouthparts would be the easiest to find in the Thylacocephala. The literature features some mention of such a head arrangement, but none definitive. Schram reports the discovery of mandibles in the Mazon Creek thylacocephalan Concavicaris georgeorum. Secrétan also mentions – with caution – possible mandibles in serial sections of Dollocaris ingens, and traces of small limbs in the cephalic region (not well preserved enough to assess their identity). Lange et al. report a new genus and species, Thylacocephalus cymolopos, from the Upper Cretaceous of Lebanon, which has two possible pairs of antennae, but note the possession of two pairs of antennae alone does not prove the class occupies a position in the crown-group Crustacea.
Despite a lack of evidence for a crustacean body plan, several authors have aligned the class with different groups of crustaceans. Schram provides an overview of possible affinities:
Nothing in either Uniramia or Cheliceriformes seems likely.
Conchostraca is possible, but there is no strong supporting evidence.
A maxillopodan connection is possible. Largely considered due to the Italian researchers' insistence (see disagreements).
Stomatopods show many parallels but have no comparison to cephalon or body regions.
Remipedes show some parallels.
Decapod-like gills suggest malacostracan affinities.
In these various interpretations, numerous different limb arrangements for the three raptorials have been proposed:
antennules, antennae and mandibles
antennules, antennae and maxillipeds
thoracic (in keeping with stromatopod analogies)
maxillules, maxillae, maxillipedes
Further work is necessary to provide any solid conclusions.
A study in 2022 describing a new arthropod from Wisconsin, Acheronauta, found that the Thylacocephalans occupied a position more primitive than the crustaceans and myriapods as basal stem-group mandibulates. This would place them outside of the crustaceans as a more basal branch of the arthropod family tree.
This cladogram represents the placement of the Thylacocephalans within the arthropoda as suggested by Pulsipher, 2022. | Thylacocephala | Wikipedia | 505 | 7149700 | https://en.wikipedia.org/wiki/Thylacocephala | Biology and health sciences | Fossil arthropods | Animals |
Disagreements
Numerous conflicts of opinion surround the Thylacocephala, of which the split between the “Italian school” and rest of the world is the most notable. Based on poorly preserved Ostenocaris cypriformis fossils from the Osteno deposits of Lombardy, Pinna et al. erected the class Thylacocephala. Based on inferred cirripede affinities the authors concluded the frontal lobed structure was not an eye, but a 'cephalic sac'. This opinion arose from the misinterpretation of the stomach as a reproductive organ (its contents included vertebral elements of fish, thought to be ovarian eggs). Such an arrangement is reminiscent of cirripede crustaceans, leading the authors to suggest a sessile, filter feeding mode of life, the 'cephalic sac' used to anchor the organism to the seabed. The researchers have since conceded it is highly improbable the ovaries are situated in the head, but maintain that the frontal structure is not an eye. Instead they suggest the 'cephalic sac' is covered with microsclerites, their arguments most recently presented in Alessandrello et al.
The structure is complex and "presumably multipurpose"
“Apart from a few features” it shows little affinity with a compound eye
There is a close connection with stomach residues, sac muscular system and outer hexagonal layer
Having a stomach between the eyes is unusual
Sclerites that should correspond to rhabdoms in 'eye theory' are interstitial to the hexagons, not at centre as would be expected for individual ommatidium.
Structural analogy with cirriped peduncle
Instead the authors suggest the sac is used to break down coarse chunks of food and reject indigestible portions. | Thylacocephala | Wikipedia | 379 | 7149700 | https://en.wikipedia.org/wiki/Thylacocephala | Biology and health sciences | Fossil arthropods | Animals |
All other parties interpret this as a large compound eye, the hexagons being preserved ommatidia (all researchers agree these are the same structure). This is supported by fossils of Dollocaris ingens which are so well preserved that individual retinula cells can be discerned. The preservation is so exceptional that studies have shown the species' numerous small ommatidia, distributed over the large eyes, could reduce the angle between ommatidia, thus improve their ability to detect small objects. Of the arguments above, it is posited by opponents that eyes are complex structures, and those in the Thylacocephala display clear and numerous affinities with compound eyes in other arthropod fossils, down to a cellular level of detail. The 'cephalic sac' structure itself is poorly preserved in Osteno specimens, a possible reason for interstitial 'sclerites'. The structural analogy with a cirripede peduncle lost supporting evidence when the 'ovaries' were shown to be alimentary residues, and the sac muscular system could be used to support the eyes. The unusual position of the stomach is thus the strongest inconsistency, but the Thylacocephala are defined by their unusual features, so this is not inconceivable. Further, Rolfe suggests the eyes' position can be explained if they have a large posterior area of attachment, while Schram suggests that the stomach region extending into the cephalic sac could result from an inflated foregut or anteriorly directed caecum.
Discussion of the matter has ceased in the last decade, and most researchers accept the anterior structure is an eye. Confusion is most likely the result of differing preservation in Osteno.
Mode of life
Numerous modes of life have been suggested for the Thylacocephala.
Secrétan suggested Dollocaris ingens was too large to swim, so inferred a predatory 'lurking' mode of life, lying in wait on the sea bed and then springing out to capture prey. The author also suggested it could be necrophagous, supported by Alessandrello et al., who suggest they would have been incapable of directly killing the shark remains found in the Osteno specimens' alimentary residues. Instead they surmise the Thylacocephala could have ingested shark vomit which included such remains. | Thylacocephala | Wikipedia | 494 | 7149700 | https://en.wikipedia.org/wiki/Thylacocephala | Biology and health sciences | Fossil arthropods | Animals |
Vannier et al. note the Thylacocephala possess features which would suggest adaptations for swimming in dim-light environments – a thin, non-mineralized carapace, well-developed rostral spines for possible buoyancy control in some species, a battery of pleopods for swimming, and large prominent eyes. This is supported by the Cretaceous species from Lebanon, which show adaptations for swimming, and possibly schooling.
Rolfe provides many possibilities, but concludes a realistic mode of life is mesopelagic, by analogy with hyperiid amphipods. Further suggests floor-dwelling is also possible, and that the organism could rise to catch prey during the day and return to the sea floor at night. Another notable proposal is that, like hyperiids, the class could gain oil from their food source for buoyancy, an idea supported by their diet (known from stomach residues containing shark and coleoid remains, and other Thylacocephala).
Alessandrello et al. suggest a head-down, semi-sessile life on a soft bottom, in agreement with that of Pinna et al., based on cirripede affinities. A necrophagous diet is suggested.
Briggs & Rolfe report that all the Gogo formation Thylacocephala are found in a reef formation, suggesting a shallow water environment. The authors speculate that due to the terracing of the carapace an infaunal mode of life is possible, or the ridges could provide more friction for hiding in crevices of rock.
Schram suggests a dichotomy in size of the class results from different environments; larger Thylacocephala could have lived in a fluid characterized by turbulent flow, and relied on single power stroke of trunk limbs to position themselves. He suggests that smaller forms may have resided in a viscous medium, characterized by laminar flow, and used a lever to generate the speed necessary to capture prey. | Thylacocephala | Wikipedia | 411 | 7149700 | https://en.wikipedia.org/wiki/Thylacocephala | Biology and health sciences | Fossil arthropods | Animals |
A limb (from Old English lim, meaning "body part") is a jointed, muscled appendage of a tetrapod vertebrate animal used for weight-bearing, terrestrial locomotion and physical interaction with other objects. The distalmost portion of a limb is known as its extremity. The limbs' bony endoskeleton, known as the appendicular skeleton, is homologous among all tetrapods, who use their limbs for walking, running and jumping, swimming, climbing, grasping, touching and striking.
All tetrapods have four limbs that are organized into two bilaterally symmetrical pairs, with one pair at each end of the torso, which phylogenetically correspond to the four paired fins (pectoral and pelvic fins) of their fish (sarcopterygian) ancestors. The cranial pair (i.e. closer to the head) of limbs are known as the forelimbs or front legs, and the caudal pair (i.e. closer to the tail or coccyx) are the hindlimbs or back legs. In animals with a more erect bipedal posture (mainly hominid primates, particularly humans), the forelimbs and hindlimbs are often called upper and lower limbs, respectively. The fore-/upper limbs are connected to the thoracic cage via the pectoral/shoulder girdles, and the hind-/lower limbs are connected to the pelvis via the hip joints. Many animals, especially the arboreal species, have prehensile forelimbs adapted for grasping and climbing, while some (mostly primates) can also use hindlimbs for grasping. Some animals (birds and bats) have expanded forelimbs (and sometimes hindlimbs as well) with specialized feathers or membranes to achieve lift and fly. Aquatic and semiaquatic tetrapods usually have limb features (such as webbings) adapted to better provide propulsion in water, while marine mammals and sea turtles have convergently evolved flattened, paddle-like limbs known as flippers. | Limb (anatomy) | Wikipedia | 430 | 13280372 | https://en.wikipedia.org/wiki/Limb%20%28anatomy%29 | Biology and health sciences | External anatomy and regions of the body | Biology |
In human anatomy, the upper and lower limbs are commonly known as the arms and legs respectively, although in academic usage, these terms refer specifically to the upper arm and lower leg (the lower arm and upper leg are instead called forearm and thigh, respectively). The human arms have relatively great ranges of motion and are highly adapted for grasping and for carrying objects. The extremity of each arm, known as the hand, has five opposable digits known as fingers (made up of metacarpal and metatarsal bones for hands and feet respectively) and specializes in intrinsic fine motor skills for precise manipulation of objects. The human legs and their extremities — the feet — are specialized for bipedal locomotion. Compared to most other mammals that walk and run on all four limbs, human limbs are proportionally weaker but very mobile and versatile, and the unique dexterity of the human upper extremities allows them to make sophisticated tools and machines that compensate for the lack of physical strength and endurance.
Anatomy
Limbs are attached to the torso via girdles, either the pectoral girdle for the forelimbs, or the pelvic girdle for the hindlimbs. In terrestrial tetrapods, the pectoral girdles are more mobile, floating over the rib cage connected only via the clavicles (to the sternum) and numerous muscles; while the pelvic girdles are typically fused together anteriorly via a fibrocartilaginous joint and posteriorly with the vertebral column (sacrum), forming an immobile ring-like pelvis. The girdles are each connected to the corresponding limb proper via a ball-and-socket synovial joint. | Limb (anatomy) | Wikipedia | 357 | 13280372 | https://en.wikipedia.org/wiki/Limb%20%28anatomy%29 | Biology and health sciences | External anatomy and regions of the body | Biology |
The overall patterns of forelimbs and hindlimbs are homologous among all tetrapods, as they all branched out of the same bottlenecked lineage of stegocephalians that survived the Late Devonian extinction. The body plan of tetrapod limbs are so similar (especially the pentadactyly) that they are given shared terminologies for each component of the appendicular skeleton.
The proximal half of the limb proper has one long bone, the stylopodium (plural: stylopodia), which may be the humerus of the upper arm (proximal forelimbs), or the femur of the thigh (proximal hindlimbs).
The distal half of the limb proper has two long bones, together termed the zeugopodium (plural: zeugopodia). These may be radius and ulna of the forearm, or the tibia and fibula of the shin.
The distalmost portion or extremity of the limb, i.e. the hand or foot, is known as the autopodium (plural: autopodia). Hands are technically known as the manus, and feet as the pes.
The proximal part of the autopodium, i.e. the wrist or ankle region, has many small nodular bones, collectively termed the mesopodium (plural: mesopodia). Wrist bones are known as the carpals, and ankle bones are known as the tarsals.
The middle part of the autopodium is the metapodium (plural: metapodia), composed of the slender long bones each called a metapodial. The metapodials of the hand are known as metacarpals, while the metapodials of the foot are known as metatarsals. The ventral (or flexor) aspect of the hand is known as the palm or , and that of the foot as the sole or .
The distalmost part of the autopodium are the digits (fingers or toes), which have multi-jointed phalanges and are highly mobile in most tetrapods. The ends of the digits are often protectively covered by hardened keratin outgrowths such as claws and nails.
Development | Limb (anatomy) | Wikipedia | 475 | 13280372 | https://en.wikipedia.org/wiki/Limb%20%28anatomy%29 | Biology and health sciences | External anatomy and regions of the body | Biology |
Limb development is controlled by Hox genes. All jawed vertebrates surveyed so far organize their developing limb buds in a similar way. Growth occurs from proximal to distal part of the limb. On the distal end, the differentiation of skeletal elements occurs in an apical ectodermal ridge (AER) which expands in rays. A Zone of Polarizing Activity (ZPA) at the rear part of the AER coordinates the differentiation of digits. | Limb (anatomy) | Wikipedia | 93 | 13280372 | https://en.wikipedia.org/wiki/Limb%20%28anatomy%29 | Biology and health sciences | External anatomy and regions of the body | Biology |
The wild water buffalo (Bubalus arnee), also called Asian buffalo, Asiatic buffalo and wild buffalo, is a large bovine native to the Indian subcontinent and Southeast Asia. It has been listed as Endangered in the IUCN Red List since 1986, as the remaining population totals less than 4,000. A population decline of at least 50% over the last three generations (24–30 years) is projected to continue. The global population has been estimated at 3,400 individuals, of which 95% live in India, mostly in Assam. The wild water buffalo is the most likely ancestor of the domestic water buffalo.
Taxonomy
Bos arnee was the scientific name proposed by Robert Kerr in 1792 who described a skull with horns of a buffalo zoological specimen from Bengal in northern India. The specific name arnee is derived from Hindi arnī, which referred to a female wild water buffalo; the term is related to Sanskrit áraṇya ("forest") and áraṇa ("strange, foreign.") Bubalus arnee was proposed by Charles Hamilton Smith in 1827 who introduced the generic name Bubalus for bovids with large heads, convex-shaped narrow foreheads, laterally bent flat horns, funnel-shaped ears, small dewlaps and slender tails.
Later authors subordinated the wild water buffalo under either Bos, Bubalus or Buffelus.
In 2003, the International Commission on Zoological Nomenclature placed Bubalus arnee on the Official List of Specific Names in Zoology, recognizing the validity of this name for a wild species. Most authors have adopted the binomen Bubalus arnee for the wild water buffalo as valid for the taxon.
The wild water buffalo is the most likely ancestor of the domestic water buffalo.
Only a few DNA sequences are available from wild water buffalo populations. Wild populations are considered to be the progenitor of the modern domestic water buffalo, but the genetic variation within the species is unclear, and also how it is related to the domesticated river and Carabao swamp buffaloes.
Characteristics | Wild water buffalo | Wikipedia | 413 | 13283176 | https://en.wikipedia.org/wiki/Wild%20water%20buffalo | Biology and health sciences | Bovidae | Animals |
The wild water buffalo has an ash-gray to black skin. The moderately long, coarse and sparse hair is directed forward from the haunches to the long and narrow head. There is a tuft on the forehead, and the ears are comparatively small. Its head-to-body-length is with a long tail and a shoulder height of . Both sexes carry horns that are heavy at the base and widely spreading up to along the outer edges, exceeding in size the horns of any other living bovid. The tip of the tail is bushy; the hooves are large and splayed.
It is larger and heavier than the domestic water buffalo, and weighs from . The average weight of three captive wild water buffaloes was .
It is among the heaviest living wild bovid species, and is slightly smaller than gaur.
Distribution and habitat
The wild water buffalo occurs in India, Nepal, Bhutan, Thailand, and Cambodia, with an unconfirmed population in Myanmar. It has been extirpated in Bangladesh, Laos, Vietnam, and Sri Lanka. It is associated with wet grasslands, swamps, flood plains and densely vegetated river valleys.
India hosts 95% of the total global wild buffalo population, with over 2,600 wild water buffaloes in Assam. It is largely restricted to in and around Kaziranga, Manas and Dibru-Saikhowa National Parks, Laokhowa Wildlife Sanctuary and Bura Chapori Wildlife Sanctuary and in a few scattered pockets in Assam, and in and around D'Ering Memorial Wildlife Sanctuary in Arunachal Pradesh. A small population survives in Balphakram National Park in Meghalaya, and in Chhattisgarh in Indravati National Park and Udanti Wildlife Sanctuary. This population might extend into adjacent parts of Odisha and Gadchiroli District of Maharashtra. In the early 1990s, there may still have been about 3,300–3,500 wild water buffaloes in Assam and the adjacent states of northeast India. In 1997, the number was assessed at less than 1,500 mature individuals.
Many surviving populations are thought to have interbred with feral or domestic water buffaloes. In the late 1980s, fewer than 100 wild water buffaloes were left in Madhya Pradesh. By 1992, only 50 animals were estimated to have survived there. | Wild water buffalo | Wikipedia | 471 | 13283176 | https://en.wikipedia.org/wiki/Wild%20water%20buffalo | Biology and health sciences | Bovidae | Animals |
Nepal's only population lives in Koshi Tappu Wildlife Reserve and has grown from 63 individuals in 1976 to 219 individuals in 2009. In 2016, 18 individuals were translocated from Koshi Tappu Wildlife Reserve to Chitwan National Park.
In and around Bhutan's Royal Manas National Park, a small number of wild water buffaloes occur. This is part of the sub-population that occurs in India's Manas National Park. In Myanmar, a few animals live in Hukaung Valley Wildlife Sanctuary.
In Thailand, wild water buffaloes have been reported to occur in small herds of less than 40 individuals. A population of 25–60 individuals inhabited lowland areas of the Huai Kha Khaeng Wildlife Sanctuary between December 1999 and April 2001. This population has not grown significantly in 15 years, and is maybe interbreeding with domestic water buffaloes.
The population in Cambodia is confined to a small area of easternmost Mondulkiri and possibly Ratanakiri Provinces. Only a few dozen individuals remain.
The wild water buffaloes in Sri Lanka are thought to be descendants of the introduced domestic water buffalo. It is unlikely that any true wild water buffaloes remain there today.
Wild-living populations found elsewhere in Asia, Australia, Argentina and Bolivia are feral domestic water buffaloes.
Ecology and behavior
Wild water buffaloes are both diurnal and nocturnal. Adult females and their young form stable clans of as many as 30 individuals which have home ranges of , including areas for resting, grazing, wallowing, and drinking. Clans are led by old cows, even when bulls accompany the group. Several clans form a herd of 30 to 500 animals that gather at resting areas. Adult males form bachelor groups of up to 10 individuals, with older males often being solitary, and spend the dry season apart from the female clans. They are seasonal breeders in most of their range, typically in October and November. However, some populations breed year round. Dominant males mate with the females of a clan who subsequently drive them off. Their gestation period is 10 to 11 months, with an inter-birth interval of one year. They typically give birth to a single offspring, although twins are possible. Age at sexual maturity is 18 months for males, and three years for females. The maximum known lifespan is 25 years in the wild. In Assam, herd sizes vary from three to 30 individuals. | Wild water buffalo | Wikipedia | 483 | 13283176 | https://en.wikipedia.org/wiki/Wild%20water%20buffalo | Biology and health sciences | Bovidae | Animals |
They are probably grazers by preference, feeding mainly on graminoids when available, such as Bermuda grass, and Cyperus sedges, but they also eat other herbs, fruits, and bark, as well as browsing on trees and shrubs. They also feed on crops, including rice, sugarcane, and jute, sometimes causing considerable damage.
Tigers and mugger crocodiles prey on adult wild water buffaloes, and Asian black bears have also been known to kill them.
Threats
A population reduction by at least 50% over the last three generations seems likely given the severity of the threats, especially hybridization; this population trend is projected to continue into the future. The most important threats are:
interbreeding with feral and domestic water buffaloes in and around protected areas;
hunting, especially in Thailand, Cambodia, and Myanmar;
habitat loss of floodplain areas due to conversion to agriculture and hydropower development;
degradation of wetlands due to invasive species such as stem twiners and lianas;
diseases and parasites transmitted by domestic livestock;
interspecific competition for food and water between wild water buffaloes and livestock.
Conservation
Bubalus arnee is included in CITES Appendix III, and is legally protected in Bhutan, India, Nepal, and Thailand.
In 2017, 15 wild water buffaloes were reintroduced into Chitwan National Park in Nepal to establish a second viable sub-population in the country.
In 2023, 4 wild buffalos were translocated to Udanti-Sitanadi Tiger Reserve to reverse its declining population in the state. | Wild water buffalo | Wikipedia | 315 | 13283176 | https://en.wikipedia.org/wiki/Wild%20water%20buffalo | Biology and health sciences | Bovidae | Animals |
Universal Flash Storage (UFS) is a flash storage specification for digital cameras, mobile phones and consumer electronic devices. It was designed to bring higher data transfer speed and increased reliability to flash memory storage, while reducing market confusion and removing the need for different adapters for different types of cards. The standard encompasses both packages permanently embedded (via ball grid array package) within a device (), and removable UFS memory cards.
Overview
UFS uses NAND flash. It may use multiple stacked 3D TLC NAND flash dies (integrated circuits) with an integrated controller.
The proposed flash memory specification is supported by consumer electronics companies such as Nokia, Sony Ericsson, Texas Instruments, STMicroelectronics, Samsung, Micron, and SK Hynix. UFS is positioned as a replacement for and SD cards. The electrical interface for UFS uses the M-PHY, developed by the MIPI Alliance, a high-speed serial interface targeting 2.9 Gbit/s per lane with up-scalability to 5.8 Gbit/s per lane. UFS implements a full-duplex serial LVDS interface that scales better to higher bandwidths than the 8-lane parallel and half-duplex interface of . Unlike eMMC, Universal Flash Storage is based on the SCSI architectural model and supports SCSI Tagged Command Queuing. The standard is developed by, and available from, the JEDEC Solid State Technology Association.
Software support
The Linux kernel supports UFS. OpenBSD 7.3 and later support UFS. Windows 10 and later support UFS.
History
In 2010, the Universal Flash Storage Association (UFSA) was founded as an open trade association to promote the UFS standard.
In September 2013, JEDEC published JESD220B UFS 2.0 (update to UFS v1.1 standard published in June 2012). JESD220B Universal Flash Storage v2.0 offers increased link bandwidth for performance improvement, a security features extension and additional power saving features over the UFS v1.1. | Universal Flash Storage | Wikipedia | 424 | 13288318 | https://en.wikipedia.org/wiki/Universal%20Flash%20Storage | Technology | Non-volatile memory | null |
On 30 January 2018 JEDEC published version 3.0 of the UFS standard, with a higher 11.6 Gbit/s data rate per lane (1450 MB/s) with the use of MIPI M-PHY v4.1 and UniProSM v1.8. At the MWC 2018, Samsung unveiled embedded UFS () v3.0 and uMCP (UFS-based multi-chip package) solutions.
On 30 January 2020 JEDEC published version 3.1 of the UFS standard. UFS 3.1 introduces Write Booster, Deep Sleep, Performance Throttling Notification and Host Performance Booster for faster, more power efficient and cheaper UFS solutions. The Host Performance Booster feature is optional. Before the UFS 3.1 standard, the SLC cache feature is optional on UFS device, which is a de facto feature on personal SSDs.
In 2022 Samsung announced version 4.0 doubling from 11.6 Gbit/s to 23.2 Gbit/s with the use of MIPI M-PHY v5.0 and UniPro v2.0. UFS 4.0 introduces File Based Optimization.
As of Q2 2024, Zoned UFS (ZUFS) is in development by SK hynix.
Notable devices
In February 2013, semiconductor company Toshiba Memory (now Kioxia) started shipping samples of a 64 GB NAND flash chip, the first chip to support the then new UFS standard.
In April 2015, Samsung's Galaxy S6 family was the first phone to ship with storage using the UFS 2.0 standard.
On 7 July 2016, Samsung announced its first UFS cards, in 32, 64, 128, and 256 GB storage capacities. The cards were based on the UFS 1.0 Card Extension Standard. The 256 GB version was reported to offer sequential read performance up to 530 MB/s and sequential write performance up to 170 MB/s and random performance of 40,000 read IOPS and 35,000 write IOPS. However, they were apparently not actually released to the public.
On 17 November 2016, Qualcomm announced the Snapdragon 835 SoC with support for UFS 2.1. | Universal Flash Storage | Wikipedia | 461 | 13288318 | https://en.wikipedia.org/wiki/Universal%20Flash%20Storage | Technology | Non-volatile memory | null |
On 14 May 2019, OnePlus introduced the OnePlus 7 and OnePlus 7 Pro, the first phones to feature built-in 3.0 (The Galaxy Fold, originally planned to be the first smartphone to feature UFS 3.0 was ultimately delayed after the OnePlus 7's launch).
The first UFS cards began to be publicly sold in early 2020. According to a Universal Flash Storage Association press release, Samsung planned to transition its products to UFS cards during 2020. Several consumer devices with UFS card slots have been released in 2020.
On 08 December 2022, IQOO announced the IQOO 11 which was the first phone to release with UFS 4.0 Storage. After that, other Android OEMs started using this storage solution on their flagship to upper mid-range category smartphones.
Version comparison
UFS
UFS Card
Implementation
UFS 2.0 has been implemented in Snapdragon 820 and 821. Kirin 950 and 955. Exynos 7420. NVIDIA Jetson AGX Xavier SOMs
UFS 2.1 has been implemented in Snapdragon 712 (710&720G), 730G, 732G, 835, 845 and 855. Kirin 960, 970 and 980. Exynos 9609, 9610, 9611, 9810 and 980.
UFS 3.0 has been implemented in Snapdragon 855, 855+, 860, 865, Exynos 9820–9825, and Kirin 990.
UFS 3.1 has been implemented in Snapdragon 855+/860, Snapdragon 865, Snapdragon 870, Snapdragon 888, Exynos 2100, and Exynos 2200.
UFS 4.0 has been implemented in MediaTek Dimensity 9200, MediaTek Dimensity 8300 and Snapdragon 8 Gen 2.
Complementary UFS standards
On 30 March 2016, JEDEC published version 1.0 of the UFS Card Extension Standard (JESD220-2), which offered many of the features and much of the same functionality as the existing UFS 2.0 embedded device standard, but with additions and modifications for removable cards. | Universal Flash Storage | Wikipedia | 467 | 13288318 | https://en.wikipedia.org/wiki/Universal%20Flash%20Storage | Technology | Non-volatile memory | null |
Also in March 2016, JEDEC published version 1.1 of the UFS Unified Memory Extension (JESD220-1A), version 2.1 of the UFS Host Controller Interface (UFSHCI) standard (JESD223C), and version 1.1A of the UFSHCI Unified Memory Extension standard (JESD223-1A).
On January 30, 2018, the UFS Card Extension standard was updated to version 1.1 (JESD220-2A), and the UFSHCI standard was updated to version 3.0 (JESD223D), to align with UFS version 3.0.
Rewrite cycle life
A UFS drive's rewrite life cycle affects its lifespan. There is a limit to how many write/erase cycles a flash block can accept before it produces errors or fails altogether. Each write/erase cycle causes a flash memory cell's oxide layer to deteriorate. The reliability of a drive is based on three factors: the age of the drive, total terabytes written over time and drive writes per day. This is typical of flash memory in general. | Universal Flash Storage | Wikipedia | 237 | 13288318 | https://en.wikipedia.org/wiki/Universal%20Flash%20Storage | Technology | Non-volatile memory | null |
Sodium citrate may refer to any of the sodium salts of citric acid (though most commonly the third):
Monosodium citrate
Disodium citrate
Trisodium citrate
The three forms of salt are collectively known by the E number E331.
Applications
Food
Sodium citrates are used as acidity regulators in food and drinks, and also as emulsifiers for oils. They enable cheeses to melt without becoming greasy and also reduce the acidity of food. They are generally considered safe and are designated GRAS by the FDA.
Blood clotting inhibitor
Sodium citrate is used to prevent donated blood from clotting in storage, and can also be used as an additive for apheresis to prevent clots forming in the tubes of the machine. By binding with calcium ions in the blood it prevents the process of coagulation. It is also used as an anticoagulant for laboratory testing, in that blood samples are collected into sodium citrate-containing tubes for tests such as the PT (INR), APTT, and fibrinogen levels. Sodium citrate is used in medical contexts as an alkalinizing agent in place of sodium bicarbonate, to neutralize excess acid in the blood and urine.
Metabolic acidosis
It has applications for the treatment of metabolic acidosis and chronic kidney disease.
Ferrous nanoparticles
Along with oleic acid, sodium citrate may be used in the synthesis of magnetic Fe3O4 nanoparticle coatings. | Sodium citrate | Wikipedia | 318 | 15967917 | https://en.wikipedia.org/wiki/Sodium%20citrate | Physical sciences | Citrates | Chemistry |
The mouth is the body orifice through which many animals ingest food and vocalize. The body cavity immediately behind the mouth opening, known as the oral cavity (or in Latin), is also the first part of the alimentary canal, which leads to the pharynx and the gullet. In tetrapod vertebrates, the mouth is bounded on the outside by the lips and cheeks — thus the oral cavity is also known as the buccal cavity (from Latin , meaning "cheek") — and contains the tongue on the inside. Except for some groups like birds and lissamphibians, vertebrates usually have teeth in their mouths, although some fish species have pharyngeal teeth instead of oral teeth.
Most bilaterian phyla, including arthropods, molluscs and chordates, have a two-opening gut tube with a mouth at one end and an anus at the other. Which end forms first in ontogeny is a criterion used to classify bilaterian animals into protostomes and deuterostomes.
Development
In the first multicellular animals, there was probably no mouth or gut and food particles were engulfed by the cells on the exterior surface by a process known as endocytosis. The particles became enclosed in vacuoles into which enzymes were secreted and digestion took place intracellularly. The digestive products were absorbed into the cytoplasm and diffused into other cells. This form of digestion is used nowadays by simple organisms such as Amoeba and Paramecium and also by sponges which, despite their large size, have no mouth or gut and capture their food by endocytosis.
However, most animals have a mouth and a gut, the lining of which is continuous with the epithelial cells on the surface of the body. A few animals which live parasitically originally had guts but have secondarily lost these structures. The original gut of diploblastic animals probably consisted of a mouth and a one-way gut. Some modern invertebrates still have such a system: food being ingested through the mouth, partially broken down by enzymes secreted in the gut, and the resulting particles engulfed by the other cells in the gut lining. Indigestible waste is ejected through the mouth. | Mouth | Wikipedia | 470 | 9293603 | https://en.wikipedia.org/wiki/Mouth | Biology and health sciences | Digestive system | null |
In animals at least as complex as an earthworm, the embryo forms a dent on one side, the blastopore, which deepens to become the archenteron, the first phase in the formation of the gut. In deuterostomes, the blastopore becomes the anus while the gut eventually tunnels through to make another opening, which forms the mouth. In the protostomes, it used to be thought that the blastopore formed the mouth (proto– meaning "first") while the anus formed later as an opening made by the other end of the gut. More recent research, however, shows that in protostomes the edges of the slit-like blastopore close up in the middle, leaving openings at both ends that become the mouth and anus.
Anatomy
Invertebrates
Apart from sponges and placozoans, almost all animals have an internal gut cavity, which is lined with gastrodermal cells. In less advanced invertebrates such as the sea anemone, the mouth also acts as an anus. Circular muscles around the mouth are able to relax or contract in order to open or close it. A fringe of tentacles thrusts food into the cavity and it can gape widely enough to accommodate large prey items. Food passes first into a pharynx and digestion occurs extracellularly in the gastrovascular cavity. Annelids have simple tube-like guts, and the possession of an anus allows them to separate the digestion of their foodstuffs from the absorption of the nutrients.
Many molluscs have a radula, which is used to scrape microscopic particles off surfaces. In invertebrates with hard exoskeletons, various mouthparts may be involved in feeding behaviour. Insects have a range of mouthparts suited to their mode of feeding. These include mandibles, maxillae and labium and can be modified into suitable appendages for chewing, cutting, piercing, sponging and sucking. Decapods have six pairs of mouth appendages, one pair of mandibles, two pairs of maxillae and three of maxillipeds. Sea urchins have a set of five sharp calcareous plates, which are used as jaws and are known as Aristotle's lantern. | Mouth | Wikipedia | 464 | 9293603 | https://en.wikipedia.org/wiki/Mouth | Biology and health sciences | Digestive system | null |
Vertebrates
In vertebrates, the first part of the digestive system is the buccal cavity, commonly known as the mouth. The buccal cavity of a fish is separated from the opercular cavity by the gills. Water flows in through the mouth, passes over the gills and exits via the operculum or gill slits. Nearly all fish have jaws and may seize food with them but most feed by opening their jaws, expanding their pharynx and sucking in food items. The food may be held or chewed by teeth located in the jaws, on the roof of the mouth, on the pharynx or on the gill arches.
Nearly all amphibians are carnivorous as adults. Many catch their prey by flicking out an elongated tongue with a sticky tip and drawing it back into the mouth, where they hold the prey with their jaws. They then swallow their food whole without much chewing. They typically have many small hinged pedicellate teeth, the bases of which are attached to the jaws, while the crowns break off at intervals and are replaced. Most amphibians have one or two rows of teeth in both jaws but some frogs lack teeth in the lower jaw. In many amphibians, there are also vomerine teeth attached to the bone in the roof of the mouth.
The mouths of reptiles are largely similar to those of mammals. The crocodilians are the only reptiles to have teeth anchored in sockets in their jaws. They are able to replace each of their approximately 80 teeth up to 50 times during their lives. Most reptiles are either carnivorous or insectivorous, but turtles are often herbivorous. Lacking teeth that are suitable for efficiently chewing of their food, turtles often have gastroliths in their stomach to further grind the plant material. Snakes have a very flexible lower jaw, the two halves of which are not rigidly attached, and numerous other joints in their skull. These modifications allow them to open their mouths wide enough to swallow their prey whole, even if it is wider than they are. | Mouth | Wikipedia | 419 | 9293603 | https://en.wikipedia.org/wiki/Mouth | Biology and health sciences | Digestive system | null |
Birds do not have teeth, relying instead on other means of gripping and macerating their food. Their beaks have a range of sizes and shapes according to their diet and are composed of elongated mandibles. The upper mandible may have a nasofrontal hinge allowing the beak to open wider than would otherwise be possible. The exterior surface of beaks is composed of a thin, horny sheath of keratin. Nectar feeders such as hummingbirds have specially adapted brushy tongues for sucking up nectar from flowers.
In mammals, the buccal cavity is typically roofed by the hard and soft palates, floored by the tongue and surrounded by the cheeks, salivary glands, and upper and lower teeth. The upper teeth are embedded in the upper jaw and the lower teeth in the lower jaw, which articulates with the temporal bones of the skull. The lips are soft and fleshy folds which shape the entrance into the mouth. The buccal cavity empties through the pharynx into the oesophagus.
Other functions of the mouth
Crocodilians living in the tropics can gape with their mouths to provide cooling by evaporation from the mouth lining. Some mammals rely on panting for thermoregulation as it increases evaporation of water across the moist surfaces of the lungs, the tongue and mouth. Birds also avoid overheating by gular fluttering, flapping the wings near the gular (throat) skin, similar to panting in mammals.
Various animals use their mouths in threat displays. They may gape widely, exhibit their teeth prominently, or flash the startling colours of the mouth lining. This display allows each potential combatant an opportunity to assess the weapons of their opponent and lessens the likelihood of actual combat being necessary.
A number of species of bird use a gaping, open beak in their fear and threat displays. Some augment the display by hissing or breathing heavily, while others clap their beaks. | Mouth | Wikipedia | 405 | 9293603 | https://en.wikipedia.org/wiki/Mouth | Biology and health sciences | Digestive system | null |
Mouths are also used as part of the mechanism for producing sounds for communication. To produce sounds, air is forced from the lungs over vocal cords in the larynx. In humans, the pharynx, soft palate, hard palate, alveolar ridge, tongue, teeth and lips are termed articulators and play their part in the production of speech. Varying the position of the tongue in relation to the other articulators or moving the lips restricts the airflow from the lungs in different ways and changes the mouth's resonating properties, producing a range of different sounds. In frogs, the sounds can be amplified using sacs in the throat region. The vocal sacs can be inflated and deflated and act as resonators to transfer the sound to the outside world. A bird's song is produced by the flow of air over a vocal organ at the base of the trachea, the syrinx. For each burst of song, the bird opens its beak and closes it again afterwards. The beak may move slightly and may contribute to the resonance but the song originates elsewhere. | Mouth | Wikipedia | 229 | 9293603 | https://en.wikipedia.org/wiki/Mouth | Biology and health sciences | Digestive system | null |
Rosellas are in a genus that consists of six species and nineteen subspecies.
These colourful parrots from Australia are in the genus Platycercus.
Platycercus means "broad-tailed" or "flat-tailed", reflecting a feature common to the rosellas and other members of the broad-tailed parrot tribe. Their diet is mainly seeds and fruit.
Taxonomy
The genus was described by naturalist Nicholas Aylward Vigors in 1825; the name Platycercus derived from the Greek platykerkos meaning "broad-" or "flat-tailed", from platys "broad, wide, level, flat" and kerkos "tail of a beast". The relationships with other parrots have been unclear, with the Australian ringneck (genus Barnardius) cited as a closest relative by some, and the genus Psephotus by others; the plumage of the western rosella seen as a link to the latter genus.Early European settlers encountered the eastern rosella at Rose Hill, New South Wales, now Parramatta, and so they called it the Rosehill parakeet which became "Rosehiller", and eventually "rosella". Vigors defined the genus Platycercus in 1825, based on
the distinctive architecture of the feathers in the tail and wing, and designated the crimson rosella Platycercus elegans (as Platycercus pennantii) as the type species. The description as a flat or broad tail follows Heinrich Kuhl, who separated his psittacine specimens to a group with tails that were "narrow and cuneated", that is, a tapering wedged outline.
There are, broadly speaking, three groups of rosella species. They are the blue-cheeked species which includes elegans and caledonicus, the white-cheeked species, eximius, adscitus and venustus and the yellow-cheeked species, icterotis. The observed difference in plumage has been reinforced by molecular studies in 1987 and 2015 that place the icterotis as a basal offshoot. | Rosella | Wikipedia | 425 | 2166413 | https://en.wikipedia.org/wiki/Rosella | Biology and health sciences | Psittaciformes | Animals |
There are six species and many subspecies: Ovenden and colleagues analysed mitochondrial DNA, confirming the blue-cheeked and white-cheeked lineages. They found P. caledonicus to be basal to the other blue-cheeked forms, with P. elegans nigrescens being divergent from other subspecies of P. elegans. Also, P. venustus was basal to P. eximius and P. adscitus. However, a mitochondrial study published in 2017 found that P. eximius was the earlier offshoot of the lineage that split into P. adscitus and P. venustus, and that nonsister taxa were hence able to hybridise. In 2015, Ashlee Shipham and colleagues published a molecular study based on nuclear DNA finding that P. venustus and P. adscitus were sister species, and that P. elegans nigrescens diverged earlier than P. caledonicus.
Description
Ranging in size from , rosellas are medium-sized parrots with long tails. The feathers on their backs show an obvious scalloping appearance with colouring that differs between the species. All species have distinctive cheek patches. Sexual dimorphism is absent or slight – males and females generally have similar plumage, apart from the western rosella. The juveniles of the blue-cheeked species, and western rosella, all have a distinctive green-based plumage, while immature plumage of the white-cheeked species is merely a duller version of the adults.
Distribution and habitat
Rosellas are native to Australia and nearby islands, where they inhabit forests, woodlands, farmlands, and suburban parks and gardens. They are confined to the coastal mountains and plains and are absent from the outback. Introduced populations have also established themselves in New Zealand (notably in the North Island and in north Dunedin) and on Norfolk Island.
Behaviour and ecology
Rosellas feed predominantly on seeds and fruit, with food held in the foot. They enjoy bathing in puddles of water in the wild and in captivity. Rosellas scratch their heads with the foot behind the wing.
Mutual preening is not exhibited by the genus, and the courtship display is simple; the male waves his tail sideways, and engages in some head bobbing, and the female reciprocates. | Rosella | Wikipedia | 472 | 2166413 | https://en.wikipedia.org/wiki/Rosella | Biology and health sciences | Psittaciformes | Animals |
Like most parrots, they are cavity nesters, generally nesting high in older large trees in forested areas. They generally have a clutch size of several eggs which are incubated for around 21 days by the female alone. The male feeds the female through this time and for some time after incubation concludes. Quickly covered in a white down, chicks take around five weeks to fledge.
Aviculture
The more colourful rosella species are popular as pet parrots and also as aviary birds. They can live for longer than 20 years, and they are relatively easy to breed. All have a reputation for being aggressive in captivity, and are hence recommended be kept separate from other caged birds. Their diet in aviculture includes seeds, fruit such as apple, pear, and grapes, and vegetable matter such as lettuce, grass, and silver beet. | Rosella | Wikipedia | 178 | 2166413 | https://en.wikipedia.org/wiki/Rosella | Biology and health sciences | Psittaciformes | Animals |
Pareiasaurs (meaning "cheek lizards") are an extinct clade of large, herbivorous parareptiles. Members of the group were armoured with osteoderms which covered large areas of the body. They first appeared in southern Pangea during the Middle Permian, before becoming globally distributed during the Late Permian. Pareiasaurs were the largest reptiles of the Permian, reaching sizes equivalent to those of contemporary therapsids. Pareiasaurs became extinct in the Permian–Triassic extinction event.
Description
Pareiasaurs ranged in size from long, with some species estimated to exceed in body mass. The limbs of many parieasaurs were extremely robust, likely to account for the increased stress on their limbs caused by their typically sprawling posture. The cow-sized Bunostegos differed from other pareiasaurs by having a more upright limb posture, being amongst the first amniotes to develop this trait. Pareiasaurs were protected by bony scutes called osteoderms that were set into the skin. Their skulls were heavily ornamented with bosses, rugose ridges, and bumps. Their leaf-shaped multi-cusped teeth resemble those of iguanas, indicating a herbivorous diet. The body probably housed an extensive digestive tract. Most authors have assumed a terrestrial lifestyle for pareiasaurs. A 2008 bone microanatomy study suggested a more aquatic, plausibly amphibious lifestyle, but a later 2019 study found that the bone histology provided no direct evidence of this lifestyle. | Pareiasauria | Wikipedia | 319 | 2167305 | https://en.wikipedia.org/wiki/Pareiasauria | Biology and health sciences | Parareptilia | Animals |
Evolutionary history
Pareiasaurs appear very suddenly in the fossil record. It is clear that these animals are parareptiles. As such, they are closely related to nycteroleterids. Pareiasaurs filled the large herbivore niche (or guild) that had been occupied early in the Permian period by the caseid pelycosaurs and, before them, the diadectid reptiliomorphs. They are much larger than the diadectids, more similar to the giant caseid pelycosaur Cotylorhynchus. Although the last Pareiasaurs were no larger than the first types (indeed, many of the last ones became smaller), there was a definite tendency towards increased armour as the group developed. Pareiasaurs first appeared in the fossil record in the Middle Permian (Guadalupian) of Southern Pangaea, before dispersing into Northern Pangaea and gaining a cosmopolitan distribution during the Late Permian (Lopingian).
Classification
Some paleontologists considered that pareiasaurs were direct ancestors of modern turtles. Pareiasaur skulls have several turtle-like features, and in some species the scutes have developed into bony plates, possibly the precursors of a turtle shell. Jalil and Janvier, in a large analysis of pareiasaur relationships, also found turtles to be close relatives of the "dwarf" pareiasaurs, such as Pumiliopareia. However, the discovery of Pappochelys argues against a potential pareisaurian relationship to turtles, and DNA evidence indicates that living turtles are more closely related to living archosaurs than lepidosaurs, and therefore cladistically diapsids. | Pareiasauria | Wikipedia | 359 | 2167305 | https://en.wikipedia.org/wiki/Pareiasauria | Biology and health sciences | Parareptilia | Animals |
Associated clades
Hallucicrania (Lee 1995): This clade was coined by MSY Lee for Lanthanosuchidae + (Pareiasauridae + Testudines). Lee's pareiasaur hypothesis has become untenable due to the diapsid features of the stem turtle Pappochelys and the potential testudinatan nature of Eunotosaurus. Recent cladistic analyses reveal that lanthanosuchids have a much more basal position in the Procolophonomorpha, and that the nearest sister taxon to the pareiasaurs are the rather unexceptional and conventional looking nycteroleterids (Müller & Tsuji 2007, Lyson et al. 2010) the two being united in the clade Pareiasauromorpha (Tsuji et al. 2012).
Pareiasauroidea (Nopcsa, 1928): This clade (as opposed to the superfamily or suborder Pareiasauroidea) was used by Lee (1995) for Pareiasauridae + Sclerosaurus. More recent cladistic studies place Sclerosaurus in the procolophonid subfamily Leptopleuroninae (Cisneros 2006, Sues & Reisz 2008), which means the similarities with pareiasaurs are the result of convergences.
Pareiasauria (Seeley, 1988): If neither Lanthanosuchidae or Testudines are included in the clade, the Pareiasauria only contains the monophyletic family Pareiasauridae.
Phylogeny
Below is a cladogram from Tsuji et al. (2013): | Pareiasauria | Wikipedia | 342 | 2167305 | https://en.wikipedia.org/wiki/Pareiasauria | Biology and health sciences | Parareptilia | Animals |
Marine shrimp farming is an aquaculture business for the cultivation of marine shrimp or prawns for human consumption. Although traditional shrimp farming has been carried out in Asia for centuries, large-scale commercial shrimp farming began in the 1970s, and production grew steeply, particularly to match the market demands of the United States, Japan and Western Europe. The total global production of farmed shrimp reached more than 1.6 million tonnes in 2003, representing a value of nearly 9 billion U.S. dollars. About 75% of farmed shrimp is produced in Asia, in particular in China and Thailand. The other 25% is produced mainly in Latin America, where Brazil, Ecuador, and Mexico are the largest producers. The largest exporting nation is India.
Shrimp farming has changed from traditional, small-scale businesses in Southeast Asia into a global industry. Technological advances have led to growing shrimp at ever higher densities, and broodstock is shipped worldwide. Virtually all farmed shrimp are of the family Penaeidae, and just two species – Penaeus vannamei (Pacific white shrimp) and Penaeus monodon (giant tiger prawn) – account for roughly 80% of all farmed shrimp. These industrial monocultures are very susceptible to diseases, which have caused several regional wipe-outs of farm shrimp populations. Increasing ecological problems, repeated disease outbreaks, and pressure and criticism from both NGOs and consumer countries led to changes in the industry in the late 1990s and generally stronger regulation by governments. In 1999, a program aimed at developing and promoting more sustainable farming practices was initiated, including governmental bodies, industry representatives, and environmental organizations.
History and geography
Shrimp has been farmed in South East Asia and China for centuries, using traditional low-density methods. In Indonesia, the use of brackish water ponds, called tambaks, can be traced back as far as the 15th century. They used small scale ponds for monoculture or polycultured with other species, such as milkfish, or in rotation with rice, using the rice paddies for shrimp cultures during the dry season, when no rice could be grown. Such cultures often were in coastal areas or on river banks. Mangrove areas were favored because of their abundant natural shrimp. Wild juvenile shrimp were trapped in ponds and reared on naturally occurring organisms in the water until they reached the desired size for harvesting. | Marine shrimp farming | Wikipedia | 476 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
Industrial shrimp farming can be traced to the 1930s, when Japanese agrarians spawned and cultivated Kuruma shrimp (Penaeus japonicus) for the first time. By the 1960s, a small industry had developed in Japan. Commercial shrimp farming began to grow rapidly in the late 1960s and early 1970s. Technological advances led to more intensive forms of farming, and growing market demand led to worldwide proliferation of shrimp farms, concentrated in tropical and subtropical regions. Growing consumer demand in the early 1980s coincided with faltering wild catches, creating a booming industry. Taiwan was an early adopter and a major producer in the 1980s; its production collapsed beginning in 1988 due to poor management practices and disease. In Thailand, large-scale production expanded rapidly from 1985. In South America, Ecuador pioneered shrimp farming, where it expanded dramatically from 1978. Brazil had been active in shrimp farming since 1974, but trade boomed there only in the 1990s, making the country a major producer within a few years. Today, there are marine shrimp farms in over fifty countries.
Farming methods
When shrimp farming emerged to satisfy demand that had surpassed the wild fisheries' capacity, the subsistence farming methods of old were rapidly replaced by the more productive practices required to serve a global market. Industrial farming at first followed traditional methods, with so-called "extensive" farms, compensating for low density with increased pond sizes; instead of ponds of just a few hectares, ponds of sizes up to were used and huge areas of mangroves were cleared in some areas. Technological advances made more intensive practices possible that increase yield per area, helping reduce pressure to convert more land. Semi-intensive and intensive farms appeared, where the shrimp were reared on artificial feeds and ponds were actively managed. Although many extensive farms remain, new farms typically are of the semi-intensive kind.
Until the mid-1980s, most farms were stocked with young wild animals, called 'postlarvae', typically caught locally. Postlarvae fishing became an important economic sector in many countries. To counteract the depletion of fishing grounds and to ensure a steady supply of young shrimp, the industry started breeding shrimp in hatcheries.
Life cycle | Marine shrimp farming | Wikipedia | 435 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
Shrimp mature and breed only in a marine habitat. The females lay 100,000 to 500,000 eggs, which hatch after some 24 hours into tiny nauplii. These nauplii feed on yolk reserves within their bodies, and then metamorphose into zoeae. Shrimp in this second larval stage feed in the wild on algae, and after a few days, morph again into mysis larvae. The mysis larvae or myses look akin to tiny shrimp, and feed on algae and zooplankton. After another three to four days, they metamorphose a final time into postlarvae: young shrimp that have adult characteristics. The whole process takes about 12 days from hatching. In the wild, postlarvae then migrate into estuaries, which are rich in nutrients and low in salinity. They migrate back into open waters when they mature.
Supply chain
In shrimp farming, this life cycle occurs under controlled conditions. The reasons to do so include more intensive farming, improved size control resulting in more uniformly sized shrimp, and better predator control, but also the ability to accelerate growth and maturation by controlling the climate (especially in farms in the temperate zones, using greenhouses). There are three different stages:
Hatcheries breed shrimp and produce nauplii or even postlarvae, which they sell to farms. Large shrimp farms maintain their own hatcheries and sell nauplii or postlarvae to smaller farms in the region.
Nurseries grow postlarvae and accustom them to the marine conditions in the grow-out ponds.
In the grow-out ponds the shrimp are grown from juveniles to marketable size, which takes between three and six months.
Most farms produce one to two harvests a year; in tropical climates, even three are possible. Because of the need for salt water, shrimp farms are located on or near a coast. Inland shrimp farms have also been tried in some regions, but the need to ship salt water and competition for land with agricultural users led to problems. Thailand banned inland shrimp farms in 1999.
Hatcheries | Marine shrimp farming | Wikipedia | 435 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
Small-scale hatcheries are very common throughout Southeast Asia. Often run as family businesses and using a low-technology approach, they use small tanks (less than ten tons) and often low animal densities. They are susceptible to disease, but due to their small size, they can typically restart production quickly after disinfection. The survival rate is anywhere between zero and 90%, depending on a wide range of factors, including disease, the weather, and the experience of the operator.
Greenwater hatcheries are medium-sized hatcheries using large tanks with low animal densities. To feed the shrimp larvae, an algal bloom is induced in the tanks. The survival rate is about 40%.
Galveston hatcheries (named after Galveston, Texas, where they were developed) are large-scale, industrial hatcheries using a closed and tightly controlled environment. They breed the shrimp at high densities in large (15–30 t) tanks. Survival rates vary between 0% and 80%, but typically achieve 50%.
In hatcheries, the developing shrimp are fed on a diet of algae and later also brine shrimp nauplii, sometimes (especially in industrial hatcheries) augmented by artificial diets. The diet of later stages also includes fresh or freeze-dried animal protein, for example krill. Nutrition and medication (such as antibiotics) fed to the brine shrimp nauplii are passed on to the shrimp that eat them.
Nurseries
Many farms have nurseries where the postlarval shrimp are grown into juveniles for another three weeks in separate ponds, tanks, or so-called raceways. A raceway is a rectangular, long, shallow tank through which water flows continuously.
In a typical nursery, there are 150 to 200 animals per square metre. They are fed on a high-protein diet for at most three weeks before they are moved to the grow-out ponds. At that time, they weigh between one and two grams. The water salinity is adjusted gradually to that of the grow-out ponds. | Marine shrimp farming | Wikipedia | 413 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
Farmers refer to postlarvae as "PLs", with the number of days suffixed (i.e., PL-1, PL-2, etc.). They are ready to be transferred to the grow-out ponds after their gills have branched, which occurs around PL-13 to PL-17 (about 25 days after hatching). Nursing is not absolutely necessary, but is favoured by many farms because it makes for better food utilization, improves the size uniformity, helps use the infrastructure better, and can be done in a controlled environment to increase the harvest. The main disadvantage of nurseries is that some of the postlarval shrimp die upon the transfer to the grow-out pond.
Some farms do not use a nursery, but stock the postlarvae directly in the grow-out ponds after having acclimated them to the appropriate temperature and salinity levels in an acclimation tank. Over the course of a few days, the water in these tanks is changed gradually to match that of the grow-out ponds. The animal density should not exceed 500/litre for young postlarvae and 50/liter for larger ones, such as PL-15.
Grow-out
In the grow-out phase, the shrimp are grown to maturity. The postlarvae are transferred to ponds where they are fed until they reach marketable size, which takes about another three to six months. Harvesting the shrimp is done by fishing them from the ponds using nets or by draining the ponds. Pond sizes and the level of technical infrastructure vary.
Extensive shrimp farms using traditional low-density methods are invariably located on a coast and often in mangrove areas. The ponds range from just a few to more than 100 hectares; shrimp are stocked at low densities (2–3 animals per square metre, or 25,000/ha). The tides provide for some water exchange, and the shrimp feed on naturally occurring organisms. In some areas, farmers even grow wild shrimp by just opening the gates and impounding wild larvae. Prevalent in poorer or less developed countries where land prices are low, extensive farms produce annual yields from 50 to 500 kg/ha of shrimp (head-on weight). They have low production costs (US$1–3/kg live shrimp), are not very labor-intensive, and do not require advanced technical skills. | Marine shrimp farming | Wikipedia | 482 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
Semi-intensive farms do not rely on tides for water exchange, but use pumps and a planned pond layout. They can therefore be built above the high tide line. Pond sizes range from 2 to 30 ha; the stocking densities range from 10 to 30/square meter (100,000–300,000/ha). At such densities, artificial feeding using industrially prepared shrimp feeds and fertilizing the pond to stimulate the growth of naturally occurring organisms become a necessity. Annual yields range from 500 to 5,000 kg/ha, while production costs are in the range of US$2–6/kg live shrimp. With densities above 15 animals per square meter, aeration is often required to prevent oxygen depletion. Productivity varies depending upon water temperature, thus it is common to have larger sized shrimp in some seasons than in others.
Intensive farms use even smaller ponds () and even higher stocking densities. The ponds are actively managed: they are aerated, there is a high water exchange to remove waste products and maintain water quality, and the shrimp are fed on specially designed diets, typically in the form of formulated pellets. Such farms produce annual yields between 5,000 and 20,000 kg/ha; a few super-intensive farms can produce as much as 100,000 kg/ha. They require an advanced technical infrastructure and highly trained professionals for constant monitoring of water quality and other pond conditions; their production costs are in the range of US$4–8/kg live shrimp.
Estimates on the production characteristics of shrimp farms vary. Most studies agree that about 15-20% of all shrimp farms worldwide are extensive farms, another 25–30% are semi-intensive, and the rest are intensive farms. Regional variation is high, though, and Tacon reports wide discrepancies in the percentages claimed for individual countries by different studies.
Animal welfare
Eyestalk ablation is the removal of one (unilateral) or both (bilateral) eyestalks from a crustacean. It is routinely practiced on female shrimps (or prawns) in almost every marine shrimp maturation or reproduction facility in the world, both research and commercial. The aim of ablation under these circumstances is to stimulate the female shrimp to develop mature ovaries and spawn. | Marine shrimp farming | Wikipedia | 472 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
Most captive conditions for shrimp cause inhibitions in females that prevent them from developing mature ovaries. Even in conditions where a given species will develop ovaries and spawn in captivity, use of eyestalk ablation increases total egg production and increases the percentage of females in a given population that will participate in reproduction. Once females have been subjected to eyestalk ablation, complete ovarian development often ensues within as little as 3 to 10 days.
Feeding
While extensive farms mainly rely on the natural productivity of the ponds, more intensively managed farms rely on artificial shrimp feeds, either exclusively or as a supplement to the organisms that naturally occur in a pond. A food chain is established in the ponds, based on the growth of phytoplankton. Fertilizers and mineral conditioners are used to boost the growth of the phytoplankton to accelerate the growth of the shrimp. Waste from the artificial food pellets and shrimp excrement can lead to the eutrophication of the ponds.
Artificial feeds come in the form of specially formulated, granulated pellets that disintegrate quickly. Up to 70% of such pellets are wasted, as they decay before the shrimp have eaten them. They are fed two to five times daily; the feeding can be done manually either from ashore or from boats, or using mechanized feeders distributed all over a pond. The feed conversion rate (FCR), i.e. the amount of food needed to produce a unit (e.g. one kilogram) of shrimp, is claimed by the industry to be around 1.2–2.0 in modern farms, but this is an optimum value that is not always attained in practice. For a farm to be profitable, a feed conversion rate below 2.5 is necessary; in older farms or under suboptimal pond conditions, the ratio may easily rise to 4:1. Lower FCRs result in a higher profit for the farm.
Farmed species
Although there are many species of shrimp and prawn, only a few of the larger ones are actually cultivated, all of which belong to the family of penaeids (family Penaeidae), and within it to the genus Penaeus. Many species are unsuitable for farming: they are too small to be profitable, or simply stop growing when crowded together, or are too susceptible to diseases. The two species dominating the market are: | Marine shrimp farming | Wikipedia | 497 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
Pacific white shrimp (Litopenaeus vannamei, also called "whiteleg shrimp") is the main species cultivated in western countries. Native to the Pacific coast from Mexico to Peru, it grows to a size of 23 cm. L. vannamei accounts for 95% of the production in Latin America. It is easy to breed in captivity, but succumbs to the Taura disease.
Giant tiger prawn (P. monodon, also known as "black tiger shrimp") occurs in the wild in the Indian Ocean and in the Pacific Ocean from Japan to Australia. The largest of all the cultivated shrimp, it can grow to a length of 36 cm and is farmed in Asia. Because of its susceptibility to whitespot disease and the difficulty of breeding it in captivity, it is gradually being replaced by L. vannamei since 2001.
Together, these two species account for about 80% of the whole farmed shrimp production. Other species being bred are: | Marine shrimp farming | Wikipedia | 203 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
Western blue shrimp (P. stylirostris) was a popular choice for shrimp farming in the western hemisphere, until the IHHN virus wiped out nearly the whole population in the late 1980s. A few stocks survived and became resistant against this virus. When it was discovered that some of these were also resistant against the Taura virus, some farms again bred P. stylirostris from 1997 on.
Chinese white shrimp (P. chinensis, also known as the fleshy prawn) occurs along the coast of China and the western coast of Korea and is being farmed in China. It grows to a maximum length of only 18 cm, but tolerates colder water (min. 16 °C). Once a major factor on the world market, it is today used almost exclusively for the Chinese domestic market after a disease wiped out nearly all the stocks in 1993.
Kuruma shrimp (P. japonicus) is farmed primarily in Japan and Taiwan, but also in Australia; the only market is in Japan, where live Kuruma shrimp reach prices of the order of US$100 per pound ($220/kg).
Indian white shrimp (P. indicus) is a native of the coasts of the Indian Ocean and is widely bred in India, Iran and the Middle East and along the African shores.
Banana shrimp (P. merguiensis) is another cultured species from the coastal waters of the Indian Ocean, from Oman to Indonesia and Australia. It can be grown at high densities.
Several other species of Penaeus play only a very minor role in shrimp farming. Some other kinds of shrimp also can be farmed, e.g. the "Akiami paste shrimp" or Metapenaeus spp. Their total production from aquaculture is of the order of only about 25,000 tonnes per year, small in comparison to that of the penaeids.
Diseases
There are a variety of lethal viral diseases that affect shrimp. In the densely populated, monocultural farms such virus infections spread rapidly and may wipe out whole shrimp populations. A major transfer vector of many of these viruses is the water itself; and thus any virus outbreak also carries the danger of decimating shrimp living in the wild. | Marine shrimp farming | Wikipedia | 453 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
Yellowhead disease, called Hua leung in Thai, affects P. monodon throughout Southeast Asia. It had been reported first in Thailand in 1990. The disease is highly contagious and leads to mass mortality within 2 to 4 days. The cephalothorax of an infected shrimp turns yellow after a period of unusually high feeding activity ending abruptly, and the then moribund shrimp congregate near the surface of their pond before dying.
Early mortality syndrome (EMS) has been linked to a strain of a bacterium called Vibrio parahaemolyticus which affects the Giant Tiger Prawn and the Whiteleg Shrimp, both shrimp that are commonly farmed around the world. The strains are not harmful to humans, but are economically devastating for shrimp farmers. The spread of the bacteria is more prevalent in warmer and saltier ocean waters.
Whitespot syndrome is a disease caused by a family of related viruses. First reported in 1993 from Japanese P. japonicus cultures, it spread throughout Asia and then to the Americas. It has a wide host range and is highly lethal, leading to mortality rates of 100% within days. Symptoms include white spots on the carapace and a red hepatopancreas. Infected shrimp become lethargic before they die.
Taura syndrome was first reported from shrimp farms on the Taura river in Ecuador in 1992. The host of the virus causing the disease is P. vannamei, one of the two most commonly farmed shrimp. The disease spread rapidly, mainly through the shipping of infected animals and broodstock. Originally confined to farms in the Americas, it has also been propagated to Asian shrimp farms with the introduction of L. vannamei there. Birds are thought to be a route of infection between farms within one region.
Infectious hypodermal and hematopoietic necrosis (IHHN) is a disease that causes mass mortality among P. stylirostris (as high as 90%) and severe deformations in L. vannamei. It occurs in Pacific farmed and wild shrimp, but not in wild shrimp on the Atlantic coast of the Americas. | Marine shrimp farming | Wikipedia | 434 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
There are also a number of bacterial infections that are lethal to shrimp. The most common is vibriosis, caused by bacteria of the Vibrio species. The shrimp become weak and disoriented, and may have dark wounds on the cuticle. The mortality rate can exceed 70%. Another bacterial disease is necrotising hepatopancreatitis (NHP); symptoms include a soft exoskeleton and fouling. Most such bacterial infections are strongly correlated to stressful conditions, such as overcrowded ponds, high temperatures, and poor water quality, factors that positively influence the growth of bacteria. Treatment is done using antibiotics. Importing countries have repeatedly placed import bans on shrimp containing various antibiotics. One such antibiotic is chloramphenicol, which has been banned in the European Union since 1994, but continues to pose problems.
With their high mortality rates, diseases represent a very real danger to shrimp farmers, who may lose their income for the whole year if their ponds are infected. Since most diseases cannot yet be treated effectively, the industry's efforts are focused on preventing disease outbreak in the first place. Active water quality management helps avoid poor pond conditions favorable to the spread of diseases, and instead of using larvae from wild catches, specific pathogen free broodstocks raised in captivity in isolated environments and certified not to carry diseases are used increasingly. To avoid introducing diseases into such disease-free populations on a farm, there is also a trend to create more controlled environments in the ponds of semi-intensive farms, such as by lining them with plastic to avoid soil contact, and by minimizing water exchange in the ponds.
Economy
The total global production of farmed shrimp reached 2.5 million tonnes in 2005. This accounts for 42% of the total shrimp production that year (farming and wild catches combined). The largest single market for shrimp is the United States, importing between 500 – 600,000 tonnes of shrimp products yearly in the years 2003–2009. About 200,000 tonnes yearly are imported by Japan, while the European Union imported in 2006 another about 500,000 tonnes of tropical shrimps, with the largest importers being Spain and France. The EU also is a major importer of coldwater shrimp from catches, mainly common shrimp (Crangon crangon) and Pandalidae such as Pandalus borealis; in 2006, these imports accounted for about another 200,000 tonnes. | Marine shrimp farming | Wikipedia | 495 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
The import prices for shrimp fluctuate wildly. In 2003, the import price per kilogram shrimp in the United States was US$8.80, slightly higher than in Japan at US$8.00. The average import price in the EU was only about US$5.00/kg; this much lower value is explained by the fact that the EU imports more coldwater shrimp (from catches) that are much smaller than the farmed warm water species, and thus attain lower prices. In addition, Mediterranean Europe prefers head-on shrimp, which weigh approximately 30% more, but have a lower unit price.
About 75% of the world production of farmed shrimp comes from Asian countries; the two leading nations being China and Thailand, closely followed by Vietnam, Indonesia, and India. The other 25% are produced in the western hemisphere, where Latin American countries (Brazil, Ecuador, Mexico) dominate. In terms of export, Thailand is by far the leading nation, with a market share of more than 30%, followed by China, Indonesia, and India, accounting each for about 10%. Other major export nations are Vietnam, Bangladesh, and Ecuador. Thailand exports nearly all of its production, while China uses most of its shrimp in the domestic market. The only other major export nation that has a strong domestic market for farmed shrimp is Mexico.
Disease problems have repeatedly impacted the shrimp production negatively. Besides the near-wipeout of P. chinensis in 1993, there were outbreaks of viral diseases that led to marked declines in the per-country production in 1996/97 in Thailand and repeatedly in Ecuador. In Ecuador alone, production suffered heavily in 1989 (IHHN), 1993 (Taura), and 1999 (whitespot). Another reason for sometimes wild changes in shrimp farm output are the import regulations of the destination countries, which do not allow shrimp contaminated by chemicals or antibiotics to be imported.
In the 1980s and through much of the 1990s, shrimp farming promised high profits. The investments required for extensive farms were low, especially in regions with low land prices and wages. For many tropical countries, especially those with poorer economies, shrimp farming was an attractive business, offering jobs and incomes for poor coastal populations and has, due to the high market prices of shrimp, provided many developing countries with non-negligible foreign currency earnings. Many shrimp farms were funded initially by the World Bank or substantially subsidized by local governments. | Marine shrimp farming | Wikipedia | 495 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
In the late 1990s, the economic situation changed. Governments and farmers alike were under increasing pressure from NGOs and the consumer countries, who criticized the practices of the trade. International trade conflicts erupted, such as import bans by consumer countries on shrimp containing antibiotics, the United States' shrimp import ban against Thailand in 2004 as a measure against Thai shrimp fishers not using turtle excluder devices in their nets, or the "anti-dumping" case initiated by U.S. shrimp fishers in 2002 against shrimp farmers worldwide, which resulted two years later in the U.S. imposing antidumping tariffs of the order of about 10% against many producer countries (except China, which received a 112% duty). Diseases caused significant economic losses. In Ecuador, where shrimp farming was a major export sector (the other two are bananas and oil), the whitespot outbreak of 1999 caused an estimated 130,000 workers to lose their jobs. Furthermore, shrimp prices dropped sharply in 2000. All of these factors contributed to the slowly growing acceptance by farmers that improved farming practices were needed, and resulted in tighter government regulation of the business, both of which internalized some of the external costs that were ignored during the boom years.
Socioeconomic aspects
Shrimp farming offers significant employment opportunities, which may help alleviate the poverty of the local coastal populations in many areas, if it is properly managed. The published literature on that topic shows large discrepancies, and much of the available data are of anecdotal nature. Estimates of the labor intensity of shrimp farms range from about one-third to three times more than when the same area was used for rice paddies, with much regional variation and depending on the type of farms surveyed. In general, intensive shrimp farming requires more labor per unit area than extensive farming. Extensive shrimp farms cover much more land area and are often, but not always, located in areas where no agricultural land uses are possible. Supporting industries such as feed production or storage, handling, and trade companies should also not be neglected, even if not all of them are exclusive to shrimp farming.
Typically, workers on a shrimp farm can get better wages than with other employment. A global estimate from one study is that a shrimp farm worker can earn 1.5–3 times as much as in other jobs; a study from India arrived at a salary increase of about 1.6, and a report from Mexico states the lowest paid job at shrimp farms was paid in 1996 at 1.22 times the average worker salary in the country. | Marine shrimp farming | Wikipedia | 509 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
NGOs have frequently criticized that most of the profits went to large conglomerates instead of to the local population. While this may be true in certain regions, such as Ecuador, where most shrimp farms are owned by large companies, it does not apply in all cases. For instance in Thailand, most farms are owned by small local entrepreneurs, although there is a trend to vertically integrate the industries related to shrimp farming from feed producers to food processors and trade companies. A 1994 study reported a farmer in Thailand could increase their income by a factor of ten by switching from growing rice to farming shrimp. An Indian study from 2003 arrives at similar figures for shrimp farming in the East Godavari district in Andhra Pradesh.
Whether the local population benefits from shrimp farming is also dependent on the availability of sufficiently trained people. Extensive farms tend to offer mainly seasonal jobs during harvest that do not require much training. In Ecuador, many of these positions are known to have been filled by migrant workers. More intensive farms have a need for year-round labor in more sophisticated jobs.
Marketing
For commercialization, shrimp are graded and marketed in different categories. From complete shrimp (known as "head-on, shell-on" or HOSO) to peeled and deveined (P&D), any presentation is available in stores. The animals are graded by their size uniformity and then also by their count per weight unit, with larger shrimp attaining higher prices.
Ecological impacts | Marine shrimp farming | Wikipedia | 288 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
Shrimp farms of all types, from extensive to super-intensive, can cause severe ecological problems wherever they are located. For extensive farms, huge areas of mangroves were cleared, reducing biodiversity. During the 1980s and 1990s, about 35% of the world's mangrove forests had vanished. Shrimp farming was a major cause of this, accounting for over a third of it according to one study; other studies report between 5% and 10% globally, with enormous regional variability. Other causes of mangrove destruction are population pressure, logging, pollution from other industries, or conversion to other uses such as salt pans. Mangroves, through their roots, help stabilize a coastline and capture sediments; their removal has led to a marked increase of erosion and less protection against floods. Mangrove estuaries are also especially rich and productive ecosystems and provide the spawning grounds for many species of fish, including many commercially important ones. Many countries have protected their mangroves and forbidden the construction of new shrimp farms in tidal or mangrove areas. The enforcement of the respective laws is often problematic, though, and especially in the least developed countries such as Bangladesh, Myanmar, or Vietnam the conversion of mangroves to shrimp farms remains an issue for areas such as the Myanmar Coast mangroves.
Intensive farms, while reducing the direct impact on the mangroves, have other problems. Their nutrient-rich effluents (industrial shrimp feeds disintegrate quickly, as little as 30% are actually eaten by the shrimp with a corresponding economic loss to the farmer, the rest is wasted) are typically discharged into the environment, seriously upsetting the ecological balance. These waste waters contain significant amounts of chemical fertilizers, pesticides, and antibiotics that cause pollution of the environment. Furthermore, releasing antibiotics in such ways injects them into the food chain and increases the risks of bacteria becoming resistant against them. However, most aquatic bacteria, unlike bacteria associated with terrestrial animals, are not zoonotic. Only a few disease transfers from animals to humans have been reported. | Marine shrimp farming | Wikipedia | 405 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
Prolonged use of a pond can lead to an incremental buildup of a sludge at the pond's bottom from waste products and excrement. The sludge can be removed mechanically, or dried and plowed to allow biodecomposition, at least in areas without acid problems. Flushing a pond never completely removes this sludge, and eventually, the pond is abandoned, leaving behind a wasteland, with the soil made unusable for any other purposes due to the high levels of salinity, acidity, and toxic chemicals. A typical pond in an extensive farm can be used only a few years. An Indian study estimated the time to rehabilitate such lands to about 30 years. Thailand has banned inland shrimp farms since 1999 because they caused too much destruction of agricultural lands due to salination. A Thai study estimated 60% of the shrimp farming area in Thailand was abandoned in the years 1989–1996. Many of these problems stem from using mangrove land that has high natural pyrite content (acid sulfate soil) and poor drainage. The shift to semi-intensive farming requires higher elevations for drain harvesting and low sulfide (pyrite) content to prevent acid formation when the soils shift from anaerobic to aerobic conditions.
The global nature of the shrimp farming business, and in particular the shipment of broodstock and hatchery products, throughout the world have not only introduced various shrimp species as exotic species, but also distributed the diseases the shrimp may carry worldwide. As a consequence, most broodstock shipments require health certificates and/or to have specific pathogen free (SPF) status. Many organizations lobby actively for consumers to avoid buying farmed shrimp; some also advocate the development of more sustainable farming methods. A joint programme of the World Bank, the Network of Aquaculture Centres in Asia-Pacific (NACA), the WWF, and the FAO was established in August 1999 to study and propose improved practices for shrimp farming. Some existing attempts at sustainable export-oriented shrimp farming marketing the shrimp as "ecologically produced" are criticized by NGOs as being dishonest and trivial window-dressing. | Marine shrimp farming | Wikipedia | 429 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
Yet, the industry has been slowly changing since about 1999. It has adopted the "best management practices" developed by the World Bank program, for example, and others. and instituted educational programs to promote them. Due to the mangrove protection laws enacted in many countries, new farms are usually of the semi-intensive kind, which are best constructed outside mangrove areas anyway. There is a trend to create even more tightly controlled environments in these farms, with the hope to achieve better disease prevention. Waste water treatment has attracted considerable attention; modern shrimp farms routinely have effluent treatment ponds where sediments are allowed to settle at the bottom and other residuals are filtered. As such improvements are costly, the World Bank program also recommends low-intensity polyculture farming for some areas. Since it has been discovered that mangrove soils are effective in filtering waste waters and tolerate high nitrate levels, the industry has also developed an interest in mangrove reforestation, although its contributions in that area are still minor. The long-term effects of these recommendations and industry trends cannot be evaluated conclusively yet.
Still, it was reported in 2012 that one pound of frozen shrimp adds one ton of carbon dioxide to the atmosphere, more than ten times that generated to produce the same weight of beef raised on cleared rainforest land.
Social changes
Shrimp farming in many cases has far-reaching effects on the local coastal population. Especially in the boom years of the 1980s and 1990s, when the business was largely unregulated in many countries, the very fast expansion of the industry caused significant changes that sometimes were detrimental to the local population. Conflicts can be traced back to two root causes: competition for common resources such as land and water, and changes induced by wealth redistribution. | Marine shrimp farming | Wikipedia | 345 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
A significant problem causing much conflict in some regions, for instance in Bangladesh, are the land use rights. With shrimp farming, a new industry expanded into coastal areas and started to make exclusive use of previously public resources. In some areas, the rapid expansion resulted in the local coastal population being denied access to the coast by a continuous strip of shrimp farms with serious impacts on the local fisheries. Such problems were compounded by poor ecological practices that caused a degradation of common resources (such as excessive use of freshwater to control the salinity of the ponds, causing the water table to sink and leading to the salination of freshwater aquifers by an inflow of salt water). With growing experience, countries usually introduced stronger governmental regulations and have taken steps to mitigate such problems, for instance through land zoning legislations. Some late adopters have even managed to avoid some problems through proactive legislation, e.g. Mexico. The situation in Mexico is unique owing to the strongly government-regulated market. Even after the liberalisation in the early 1990s, most shrimp farms are still owned and controlled by locals or local co-ops ().
Social tensions have occurred due to changes in the wealth distribution within populations. The effects of this are mixed, though, and the problems are not unique to shrimp farming. Changes in the distribution of wealth tend to induce changes in the power structure within a community. In some cases, there is a widening gap between the general population and local elites who have easier access to credits, subsidies, and permits and thus are more likely to become shrimp farmers and benefit more. In Bangladesh, on the other hand, local elites were opposing shrimp farming, which was controlled largely by an urban elite. Land concentrations in a few hands has been recognized to carry an increased risk of social and economic problems developing, especially if the landowners are non-local.
In general, it has been found that shrimp farming is accepted best and introduced most easily and with the greatest benefits for the local communities if the farms are owned by local people instead of by restricted remote élites or large companies because local owners have a direct interest in maintaining the environment and good relations with their neighbors, and because it avoids the formation of large-scale land property. | Marine shrimp farming | Wikipedia | 448 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
Sustainable practices
Although shrimp farming has disrupted social structures, it is possible for both commercial industries and independent farmers to succeed. Closed system shrimp aquaculture for instance, is becoming widely used in the US and is making its way to Southeast Asia. This system takes place indoors in moderate sized pools which efficiently circulates the water. In some cases filter feeders such as shellfish and other fish are introduced in the system, feeding off nutrients in the water that would otherwise be cycled out. This option is more environmentally safe than large scale intensive farming practices. Unfortunately, this system is capital intensive and would be difficult for small scale, independent shrimp farmers to acquire. However, this would be an excellent alternative for larger shrimp industries in Thailand.
Another alternative would be to revert to traditional shrimp farming practices, without overstocking and the use of harmful chemicals. This would be an ideal option for small scale shrimp farmers supplying for their own community as well as creating an independent food source. | Marine shrimp farming | Wikipedia | 195 | 2167405 | https://en.wikipedia.org/wiki/Marine%20shrimp%20farming | Technology | Aquaculture | null |
A freshwater prawn farm is an aquaculture business designed to raise and produce freshwater prawns or shrimp for human consumption. Freshwater prawn farming shares many characteristics with, and many of the same problems as, marine shrimp farming. Unique problems are introduced by the developmental life cycle of the main species (the giant river prawn, Macrobrachium rosenbergii).
The global annual production of freshwater prawns (excluding crayfish and crabs) in 2003 was about 280,000 tons, of which China produced some 180,000 tons, followed by India and Thailand with some 35,000 tons each. Additionally, China produced about 370,000 tons of Chinese river crab (Eriocheir sinensis).
Species
All farmed freshwater prawns today belong to the genus Macrobrachium. Until 2000, the only species farmed was the giant river prawn (Macrobrachium rosenbergii, also known as the Malaysian prawn). Since then, China has begun farming the Oriental river prawn (M. nipponense) in large quantities, and India farms a small amount of monsoon river prawn (M. malcolmsonii). In 2003, these three species accounted for all farmed freshwater prawns, about two-thirds M. rosenbergii and one-third M. nipponense.
About 200 species in the genus Macrobrachium live in the tropical and subtropical climates on all continents except Europe and Antarctica.
Biology of Macrobrachium rosenbergii
Giant river prawns live in turbid freshwater, but their larval stages require brackish water to survive.
Males can reach a body size of 32 cm; females grow to 25 cm. In mating, the male deposits spermatophores on the underside of the female's thorax, between the walking legs. The female then extrudes eggs, which pass through the spermatophores. The female carries the fertilized eggs with her until they hatch; the time may vary, but is generally less than three weeks. A large female may lay up to 100,000 eggs. | Freshwater prawn farming | Wikipedia | 431 | 2167409 | https://en.wikipedia.org/wiki/Freshwater%20prawn%20farming | Technology | Aquaculture | null |
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