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Light metro
Line 3 Scarborough was equipped with automatic train control from the outset, using the same SelTrac IS system as Vancouver's SkyTrain, meaning it could be operated autonomously. However, the TTC opted to equip each S-series train with an operator on board for door monitoring.
The future Ontario Line will use automatic train control with driverless trains. Its stations will be equipped with platform screen doors.
Light rail
When completed, Line 5 Eglinton will use Bombardier Transportation's Cityflo 650 CBTC automatic train control on the underground section of the line between Laird station and Mount Dennis station, along with the Eglinton Maintenance and Storage Facility adjacent to Mount Dennis station.
Track
Lines 1, 2 and 4the heavy-rail linesrun on tracks built to the Toronto gauge of , the same gauge used on the Toronto streetcar system. According to rail historians John F. Bromley and Jack May, the reason that the Yonge subway was built to the streetcar gauge was that between 1954 and 1965, subway bogies were maintained at the Hillcrest Complex, where the streetcar gauge was used for shop tracks. The Davisville Carhouse was not equipped to perform such heavy maintenance, and the bogies would be loaded onto a specially built track trailer for shipment between Davisville and Hillcrest. This practice ceased with the opening of the shops at the Greenwood Yard in 1965.
Line 3 Scarborough used standard-gauge tracks, as the ICTS design for the line did not allow for the interchange of rail equipment between the traditional subway system and Line 3. When its ICTS vehicles needed anything more than basic service (which could be carried out at the McCowan Yard), they were carried by truck to the Greenwood Subway Yard.
The Line 5 Eglinton and Line 6 Finch West LRT lines will be constructed with standard-gauge tracks. The projects are receiving a large part of their funding from the Ontario provincial transit authority Metrolinx and, to ensure a better price for purchasing vehicles, it wanted to have a degree of commonality with other similar projects within Ontario. The Ontario Line subway will similarly be built to standard gauge.
Facilities
The subway system has the following yards to provide storage, maintenance and cleaning for rolling stock. All yards are located above ground. | Toronto subway | Wikipedia | 457 | 584946 | https://en.wikipedia.org/wiki/Toronto%20subway | Technology | Canada | null |
In the second quarter of 2018, the City of Toronto moved to expropriate Canadian Pacific Railway's disused Obico Yard at 30 Newbridge Road / 36 North Queen Street in Etobicoke for use as a potential future yard at the western end of Line 2 Bloor–Danforth. The yard is situated immediately to the southwest of Kipling station, the western terminus of Line 2.
Safety
There are several safety systems for use by passengers in emergencies:
Emergency alarms (formerly "Passenger assistance alarms"): Located throughout all subway trainsWhen the yellow strip is pressed, an audible alarm is activated within the car, a notification is sent to the train crew and the Transit Control Centre, which in turn dispatches a tiered response. An orange light is activated on the outside of the car with the alarm for emergency personnel to see where the problem is.
Emergency power cut devices: Marked by a blue light, located at both ends of each subway platformFor use to cut DC traction power in the event a person falls or is observed at track level or any emergency where train movement into the station would be dangerous. These devices cut power in both directions for approximately one station each way.
Emergency stopping mechanisms (PGEV: passenger/guard emergency valve): Located at each end of each subway car (with exception of the Toronto Rocket trains)Will activate the emergency brakes of the vehicle stopping it in its current location (for use in extreme emergencies, such as persons trapped in doors as train departs station, doors opening in the tunnel, derailments etc.)
Passenger intercoms: Located on subway platforms and near/in elevators in stationsFor use to inform station collector of security/life safety issues
Automated external defibrillators (AEDs): Located in several subway stations near collector boothsFor use in the event someone suffers cardiac arrest
Public telephones: Located in various locations in all stations, and at the Designated Waiting Area's on each subway platform. Emergency calls can be made to 911 toll free. Phones located at the DWAs also include a "Crisis Link" button that connect callers, free of charge, to a 24-hour crisis line in the event that they are contemplating self-harm. | Toronto subway | Wikipedia | 449 | 584946 | https://en.wikipedia.org/wiki/Toronto%20subway | Technology | Canada | null |
Stations with high platforms have a crawl space under the platform edge which the TTC recommends that a person who has fallen onto the track use to avoid an oncoming train. Lying flat between the two rails is not recommended due to shallow clearances. The platform edge has a yellow strip behind which passengers should wait to avoid a fall.
Stations do not have platform screen doors, a feature which for Lines 1, 2 and 4 would require station modification, automatic train control (ATC) and a $1.35-billion investment which is not funded . ATC is needed to stop trains at a precise position along the platform to line up train doors with platform doors. , ATC has been activated along the entire length of Line 1; thus, it would be possible to install platform screen doors along Line 1. The future Ontario Line will be built to operate with ATC and will feature platform doors from its opening. The benefits of platform doors would be:
Blocking those attempting suicide or trespassers from the tracks: it takes 70 to 90 minutes to resume operations each time there is a personal injury at track level
Eliminating fires from debris falling on the tracks and the third rail
Allowing trains to enter crowded stations at speed, thus speeding up service along the line
The light-rail Line 5 Eglinton will use a guideway intrusion detection system (GIDS) to detect trespassers on the tracks on the underground sections of the line. When GIDS detects a trespasser on the tracks, it will issue an audio warning to the trespasser, provide live CCTV video to central control, and automatically stop the train without driver intervention. Each station will be equipped with multiple GIDS scanners along the station platform. There will also be GIDS scanners at each tunnel portal. In addition, there will be scanners within the yellow tactile strips along the platform edge to issue an audio warning if a person steps on it before the train has arrived.
A trial program began in 2008 with Toronto EMS and has been expanded and made permanent, with paramedics on hand at several stations during peak hours: Spadina and Bloor–Yonge (morning peak: 7am–10am) and Union and Eglinton (evening peak: 2pm–6pm). | Toronto subway | Wikipedia | 461 | 584946 | https://en.wikipedia.org/wiki/Toronto%20subway | Technology | Canada | null |
By September 2023, the TTC was making naloxone available at each subway station so that designated trained TTC staff could attempt to rescue anyone having a drug overdose. Kits containing naloxone nasal spray would be stored at station collector booths. TTC special constables would carry naloxone.
Training
Subway operators begin their training at Hillcrest with a virtual reality mockup of a Toronto Rocket car. The simulator consists of the operator cab with full functions, a door and partial interior of a subway car. The simulator is housed in a simulated subway tunnel. Construction of a new subway training centre is underway at the Wilson Complex, as part of the Toronto Rocket subway car program.
Expansion plans
Provincially supported projects
On April 10, 2019, Ontario premier Doug Ford announced rapid transit–related projects that the Province of Ontario would support with either committed or future financing. One such project is the Ontario Line, a proposed rapid transit line that has succeeded the Relief Line proposal. Initially, the project was projected to be completed in 2027, but this was later pushed back to 2030. A groundbreaking ceremony for the Ontario Line was held on March 27, 2022.
The Line 5 West Extension to Pearson Airport is a proposal to extend Line 5 Eglinton from its terminus at Mount Dennis station west along Eglinton Avenue West to the proposed Pearson Transit Hub in Mississauga. In April 2019, Ford said that he would commit funds for this proposal.
The Yonge North Subway Extension (YNSE) is a proposal to extend Line 1 Yonge–University north along Yonge Street from Finch station, the existing terminus of Line 1, to near Highway 7 in Richmond Hill. There would be new stations at Steeles Avenue, Clark Avenue, between Highway 7 and Highway 407 near Langstaff GO Station and Richmond Hill Centre Terminal (dubbed "Bridge station"), and High Tech Road. The extension was proposed in the province's 2007 MoveOntario 2020 plan. A major problem with this proposal was that Line 1 was at capacity, and the TTC said in 2016 that the proposed Relief Line and SmartTrack would both need to be in service before opening the YNSE. In 2020, a preliminary agreement was signed between the Ontario provincial government and York Region that anticipated the completion of the extension by approximately 2030. | Toronto subway | Wikipedia | 469 | 584946 | https://en.wikipedia.org/wiki/Toronto%20subway | Technology | Canada | null |
The Scarborough Subway Extension (SSE) is a proposal to replace Line 3 Scarborough with an eastward extension of Line 2 Bloor–Danforth. On October 8, 2013, Toronto City Council conducted a debate on whether to replace Line 3 with a light rail line or a subway extension. In 2014, the city council voted to extend Line 2 to Scarborough City Centre, which would result in the closure of Line 3. The SSE would be long and add one new station to Line 2 at Scarborough Town Centre. TTC and city staff finalized the precise route of the SSE in early 2017. In 2019, the Government of Ontario proposed a modified version of the proposal now known as the Line 2 East Extension (L2EE). The L2EE is long and adds three new stations, rather than one. The proposed completion deadline for the project is between 2029 and 2030.
The Line 4 East Extension to McCowan is a proposal to extend Line 4 Sheppard east along Sheppard Avenue East to McCowan Road, where it will connect with the Scarborough Subway Extension. Doug Ford said in April 2019 that he would commit funds related to this proposal.
Other active proposals
The Eglinton East LRT is a City of Toronto proposal to construct an LRT line (separate from Line 5 Eglinton) from Kennedy station east to Malvern. This proposal was originally part of the cancelled Scarborough–Malvern LRT in Transit City. It would have stations at Eglinton GO and Guildwood GO, as well as the University of Toronto Scarborough campus.
Inactive proposals
The Jane LRT is a proposed LRT line that would begin at Jane station on Line 2 and proceed north to Pioneer Village station on Line 1. While initially part of the cancelled Transit City plan, the Jane LRT is part of the 2018–2022 TTC Corporate Plan and tentatively referred to as Line 8.
The Line 4 West Extension to Sheppard West station is a proposal that would extend Line 4 Sheppard west along Sheppard Avenue West to Sheppard West station, where it would link to Line 1 Yonge–University. It is currently listed as an "unfunded future rapid transportation project" in the City of Toronto's 2013 Feeling Congested? report. | Toronto subway | Wikipedia | 447 | 584946 | https://en.wikipedia.org/wiki/Toronto%20subway | Technology | Canada | null |
The Line 6 East Extension to Finch station is a proposal that would extend Line 6 Finch West east along Finch Avenue West to Finch station, where it would link up with Line 1 Yonge–University. In March 2010, the Ontario government eliminated the proposed section of line between Finch West station and Finch station because of budget constraints. This section of the line was part of the original Transit City proposal. In 2013, this plan was revived as an "unfunded future rapid transit project" in the City of Toronto's Feeling Congested? report, meaning this extension may be constructed sometime in the future. The extension was later shown in the 2018–2022 TTC Corporate Plan with no timeline for completion.
Along with a proposal to extend Line 6 to Finch station, there was another proposal that would have extended the line farther to Don Mills station, where it would have provided a connection to Line 4 Sheppard. In May 2009, Metrolinx proposed that the line be extended from Finch station along Finch Avenue East and Don Mills Road into Don Mills station to connect with the Sheppard East LRT and create a seamless crosstown LRT line in northern Toronto to parallel the Eglinton Crosstown LRT (later designated Line 5 Eglinton) in central Toronto. The TTC said that a planning study would have commenced in 2010.
The Line 6 West Extension to Pearson Airport is a proposal that would extend Line 6 Finch West west to Pearson Airport, where it would provide a link to Line 5 Eglinton. In 2009, the TTC studied the feasibility of potential routings for a future westward extension of the Etobicoke–Finch West LRT to the vicinity of the Woodbine Live development, Woodbine Centre, and Pearson International Airport. This extension was later reclassified as a future transit project as described in the 2013 Feeling Congested? report by the City of Toronto. Metrolinx revealed in January 2020 that they would study a possible connection to the Pearson Transit Hub at Pearson Airport.
Abandoned plans
The Queen subway line was a subway line first proposed in 1911. When Line 1 was first built, a roughed-in station was included under Queen station, with the intention that the Queen subway would be the city's second subway line. The route of the Queen subway line is included in the routes for both the Relief Line and the Ontario Line proposals. | Toronto subway | Wikipedia | 476 | 584946 | https://en.wikipedia.org/wiki/Toronto%20subway | Technology | Canada | null |
The Eglinton West line was a proposed subway line in the late 1980s on which construction began in the early 1990s. It was cancelled after the election of Mike Harris as premier of Ontario. Much of its planned route is included in Line 5 Eglinton.
One proposed expansion of Line 2 Bloor–Danforth into Mississauga included eight potential stations stretching west from Kipling station to Mississauga City Centre, retrofitting some existing GO Transit stations. The plan was for the subway stations to open in 2011. Mississauga mayor Hazel McCallion and the Regional Municipality of Peel did not support the project.
The Relief Line was a proposed heavy-rail subway line running from Pape station south to Queen Street East and then west to the vicinity of Toronto City Hall. The proposal included intermediate stations at Sherbourne Street, Sumach Street, Broadview Avenue, and another near Gerrard Square. In January 2016, alignment options and possible stations were still being studied, and the project was unfunded. Construction was expected to take about ten years to complete. As early as 2008, Metrolinx chair Rob MacIsaac expressed the intent to construct the Relief Line to prevent overcrowding along Line 1. Toronto City Council also expressed support for this plan. In April 2019, the Government of Ontario under Doug Ford announced that the Ontario Line would be built instead of the Relief Line. As a result, TTC and City of Toronto staff suspended further planning work on the Relief Line in June 2019.
Transit City
The Sheppard East LRT was a proposed light rail line running east from Don Mills station to Morningside Avenue in Scarborough. The line was to be long with 25 surface stations and one underground connection at Don Mills station on Line 4 Sheppard. Construction of the Sheppard East LRT was to start upon completion of Line 6 Finch West. However, in July 2016, the Toronto Star reported the Sheppard LRT had been deferred indefinitely. In April 2019, Premier Doug Ford announced that the provincial government would extend Line 4 Sheppard to McCowan Road at some unspecified time in the future, replacing the proposed Sheppard East LRT.
The Don Mills LRT was a proposed LRT line that would have headed north from Pape station along Don Mills to Don Mills station. Its route was later incorporated into the Relief Line and Ontario Line proposals. | Toronto subway | Wikipedia | 473 | 584946 | https://en.wikipedia.org/wiki/Toronto%20subway | Technology | Canada | null |
Argentinosaurus (meaning "lizard from Argentina") is a genus of giant sauropod dinosaur that lived during the Late Cretaceous period in what is now Argentina. Although it is only known from fragmentary remains, Argentinosaurus is one of the largest known land animals of all time, perhaps the largest, measuring long and weighing . It was a member of Titanosauria, the dominant group of sauropods during the Cretaceous. It is regarded by many paleontologists as the largest dinosaur ever, and perhaps lengthwise the longest animal ever, though both claims have no concrete evidence yet.
The first Argentinosaurus bone was discovered in 1987 by a farmer on his farm near the city of Plaza Huincul. A scientific excavation of the site led by the Argentine palaeontologist José Bonaparte was conducted in 1989, yielding several back vertebrae and parts of a sacrum—fused vertebrae between the back and tail vertebrae. Additional specimens include a complete femur (thigh bone) and the shaft of another. Argentinosaurus was named by Bonaparte and the Argentine palaeontologist Rodolfo Coria in 1993; the genus contains a single species, A. huinculensis. The generic name Argentinosaurus means "Argentine lizard", and the specific name huinculensis refers to its place of discovery, Plaza Huincul.
The fragmentary nature of Argentinosaurus remains makes their interpretation difficult. Arguments revolve around the position of the recovered vertebrae within the vertebral column and the presence of accessory articulations between the vertebrae that would have strengthened the spine. A computer model of the skeleton and muscles estimated this dinosaur had a maximum speed of 7 km/h (5 mph) with a pace, a gait where the fore and hind limb of the same side of the body move simultaneously. The fossils of Argentinosaurus were recovered from the Huincul Formation, which was deposited in the middle Cenomanian to early Turonian ages (about 96 to 92 million years ago) and contains a diverse dinosaur fauna including the giant theropod Mapusaurus.
Discovery | Argentinosaurus | Wikipedia | 425 | 584992 | https://en.wikipedia.org/wiki/Argentinosaurus | Biology and health sciences | Sauropods | Animals |
The first Argentinosaurus bone, which is now thought to be a fibula (calf bone), was discovered in 1987 by Guillermo Heredia on his farm "Las Overas" about east of Plaza Huincul, in Neuquén Province, Argentina. Heredia, initially believing he had discovered petrified logs, informed the local museum, the Museo Carmen Funes, whose staff members excavated the bone and stored it in the museum's exhibition room. In early 1989, the Argentine palaeontologist José F. Bonaparte initiated a larger excavation of the site involving palaeontologists of the Museo Argentino de Ciencias Naturales, yielding a number of additional elements from the same individual. The individual, which later became the holotype of Argentinosaurus huinculensis, is catalogued under the specimen number MCF-PVPH 1.
Separating fossils from the very hard rock in which the bones were encased required the use of pneumatic hammers. The additional material recovered included seven dorsal vertebrae (vertebrae of the back), the underside of the sacrum (fused vertebrae between the dorsal and tail vertebrae) including the first to fifth and some sacral ribs, and a part of a dorsal rib (rib from the flank). These finds were also incorporated into the collection of the Museo Carmen Funes. | Argentinosaurus | Wikipedia | 271 | 584992 | https://en.wikipedia.org/wiki/Argentinosaurus | Biology and health sciences | Sauropods | Animals |
Bonaparte presented the new find in 1989 at a scientific conference in San Juan. The formal description was published in 1993 by Bonaparte and the Argentine palaeontologist Rodolfo Coria, with the naming of a new genus and species, Argentinosaurus huinculensis. The generic name means "Argentine lizard", while the specific name refers to the town Plaza Huincul. Bonaparte and Coria described the limb bone discovered in 1987 as an eroded tibia (shin bone), although the Uruguayan palaeontologist Gerardo Mazzetta and colleagues reidentified this bone as a left fibula in 2004. In 1996, Bonaparte referred (assigned) a complete femur (thigh bone) from the same locality to the genus, which was put on exhibit at the Museo Carmen Funes. This bone was deformed by front-to-back crushing during fossilization. In their 2004 study, Mazzetta and colleagues mentioned an additional femur that is housed in the La Plata Museum under the specimen number MLP-DP 46-VIII-21-3. Though not as strongly deformed as the complete femur, it preserves only the shaft and lacks its upper and lower ends. Both specimens belonged to individuals equivalent in size to the holotype individual. As of 2019, however, it was still uncertain whether any of these femora belonged to Argentinosaurus.
Description
Size
Argentinosaurus is among the largest known land animals, although its exact size is difficult to estimate because of the incompleteness of its remains. To counter this problem, palaeontologists can compare the known material with that of smaller related sauropods known from more complete remains. The more complete taxon can then be scaled up to match the dimensions of Argentinosaurus. Mass can be estimated from known relationships between certain bone measurements and body mass, or through determining the volume of models. | Argentinosaurus | Wikipedia | 380 | 584992 | https://en.wikipedia.org/wiki/Argentinosaurus | Biology and health sciences | Sauropods | Animals |
A reconstruction of Argentinosaurus created by Gregory Paul in 1994 yielded a length estimate of . Later that year, estimates by Bonaparte and Coria suggesting a hind limb length of , a trunk length (hip to shoulder) of , and an overall body length of were published. In 2006, Kenneth Carpenter reconstructed Argentinosaurus using the more complete Saltasaurus as a guide and estimated a length of . In 2008, Jorge Calvo and colleagues used the proportions of Futalognkosaurus to estimate the length of Argentinosaurus at less than . In 2013, William Sellers and colleagues arrived at a length estimate of and a shoulder height of by measuring the skeletal mount in Museo Carmen Funes. During the same year, Scott Hartman suggested that because Argentinosaurus was then thought to be a basal titanosaur, it would have a shorter tail and narrower chest than Puertasaurus, which he estimated to be about long, indicating Argentinosaurus was slightly smaller. In 2016, Paul estimated the length of Argentinosaurus at , but later estimated a greater length of or longer in 2019, restoring the unknown neck and tail of Argentinosaurus after those of other large South American titanosaurs. | Argentinosaurus | Wikipedia | 238 | 584992 | https://en.wikipedia.org/wiki/Argentinosaurus | Biology and health sciences | Sauropods | Animals |
Paul estimated a body mass of for Argentinosaurus in 1994. In 2004, Mazzetta and colleagues provided a range of and considered to be the most likely mass, making it the heaviest sauropod known from good material. In 2013, Sellers and colleagues estimated a mass of by calculating the volume of the aforementioned Museo Carmen Funes skeleton. In 2014 and 2018, Roger Benson and colleagues estimated the mass of Argentinosaurus at , but these estimates were questioned due to a very large error range and lack of precision. In 2016, using equations that estimate body mass based on the circumference of the humerus and femur of quadrupedal animals, Bernardo Gonzáles Riga and colleagues estimated a mass of based on an isolated femur; it is uncertain whether this femur actually belongs to Argentinosaurus. In the same year, Paul moderated his earlier estimate from 1994 and listed the body mass of Argentinosaurus at more than . In 2019, Paul moderated his 2016 estimate and gave a mass estimate of based on his skeletal reconstructions (diagrams illustrating the bones and shape of an animal) of Argentinosaurus in dorsal and lateral view. In 2020, Campione and Evans also yielded a body mass estimate of approximately . In 2023, Paul and Larramendi proposed that the holotype would have weighed between at maximum. They further suggested that the enigmatic, fragmentary Bruhathkayosaurus possibly weighed more, between . | Argentinosaurus | Wikipedia | 294 | 584992 | https://en.wikipedia.org/wiki/Argentinosaurus | Biology and health sciences | Sauropods | Animals |
While Argentinosaurus was definitely a massive animal, there is disagreement over whether it was the largest known titanosaur. Puertasaurus, Futalognkosaurus, Dreadnoughtus, Paralititan, "Antarctosaurus" giganteus, and Alamosaurus have all been considered to be comparable in size with Argentinosaurus by some studies, although others have found them to be notably smaller. In 2017, Carballido and colleagues considered Argentinosaurus to be smaller than Patagotitan, since the latter had a greater area enclosed by the , , and of its anterior dorsal vertebrae. However, Paul found Patagotitan to be smaller than Argentinosaurus in 2019, due to the latter's dorsal column being considerably longer. Even if Argentinosaurus was the largest-known titanosaur, other sauropods including Maraapunisaurus and a giant mamenchisaurid, may have been larger, although these are only known from very scant remains. Some diplodocids, such as Supersaurus and Diplodocus may have exceeded Argentinosaurus in length despite being considerably less massive. The mass of the blue whale, however, which can be greater than , still exceeds that of all known sauropods.
Vertebrae | Argentinosaurus | Wikipedia | 258 | 584992 | https://en.wikipedia.org/wiki/Argentinosaurus | Biology and health sciences | Sauropods | Animals |
Argentinosaurus likely possessed 10 dorsal vertebrae, like other titanosaurs. The vertebrae were enormous even for sauropods; one dorsal vertebra has a reconstructed height of and a width of , and the are up to in width. In 2019, Paul estimated the total length of the dorsal vertebral column at and the width of the pelvis at 0.6 times the combined length of the dorsal and sacral vertebral column. The dorsals were (concave at the rear) as in other macronarian sauropods. The (excavations on the sides of the centra) were proportionally small and positioned in the front half of the centrum. The vertebrae were internally lightened by a complex pattern of numerous air-filled chambers. Such camellate bone is, among sauropods, especially pronounced in the largest and longest-necked species. In both the dorsal and sacral vertebrae, very large cavities measuring were present. The dorsal ribs were tubular and cylindrical in shape, in contrast with other titanosaurs. Bonaparte and Coria, in their 1993 description, noted the ribs were hollow, unlike those of many other sauropods, but later authors argued this hollowing could also have been due to erosion after the death of the individual. Argentinosaurus, like many titanosaurs, probably had six sacral vertebrae (those in the hip region), although the last one is not preserved. The centra of the second to fifth sacral vertebrae were much reduced in size and considerably smaller than the centrum of the first sacral. The sacral ribs curved downwards. The second sacral rib was larger than the other preserved sacral ribs, though the size of the first is unknown due to its incompleteness. | Argentinosaurus | Wikipedia | 358 | 584992 | https://en.wikipedia.org/wiki/Argentinosaurus | Biology and health sciences | Sauropods | Animals |
Because of their incomplete preservation, the original position of the known dorsal vertebrae within the vertebral column is disputed. Dissenting configurations were suggested by Bonaparte and Coria in 1993; Fernando Novas and Martín Ezcurra in 2006; and Leonardo Salgado and Jaime Powell in 2010. One vertebra was interpreted by these studies as the first, fifth or third; and another vertebra as the second, tenth or eleventh, or ninth, respectively. A reasonably complete vertebra was found to be the third by the 1993 and 2006 studies, but the fourth by the 2010 study. Another vertebra was interpreted by the three studies as being part of the rear section of the dorsal vertebral column, as the fourth, or as the fifth, respectively. In 1993, two articulated (still connected) vertebrae were thought to be of the rear part of the dorsal column but are interpreted as the sixth and seventh vertebrae in the two later studies. The 2010 study mentioned another vertebra that was not mentioned by the 1993 and 2006 studies; it was presumed to belong to the rear part of the dorsal column. | Argentinosaurus | Wikipedia | 229 | 584992 | https://en.wikipedia.org/wiki/Argentinosaurus | Biology and health sciences | Sauropods | Animals |
Another contentious issue is the presence of hyposphene-hypantrum articulations, accessory joints between vertebrae that were located below the main articular processes. Difficulties in interpretation arise from the fragmentary preservation of the vertebral column; these joints are hidden from view in the two connected vertebrae. In 1993, Bonaparte and Coria said the hyposphene-hypantrum articulations were enlarged, as in the related Epachthosaurus, and had additional articular surfaces that extended downwards. This was confirmed by some later authors; Novas noted the hypantrum (a bony extension below the articular processes of the front face of a vertebra) extended sidewards and downwards, forming a much-broadened surface that connected with the equally enlarged hyposphene at the back face of the following vertebra. In 1996, Bonaparte stated these features would have made the spine more rigid and were possibly an adaptation to the giant size of the animal. Other authors argued most titanosaur genera lacked hyposphene-hypantrum articulations and that the articular structures seen in Epachthosaurus and Argentinosaurus are thickened vertebral (ridges). Sebastián Apesteguía, in 2005, argued the structures seen in Argentinosaurus, which he termed hyposphenal bars, are indeed thickened laminae that could have been derived from the original hyposphene and had the same function.
Limbs | Argentinosaurus | Wikipedia | 313 | 584992 | https://en.wikipedia.org/wiki/Argentinosaurus | Biology and health sciences | Sauropods | Animals |
The complete femur that was assigned to Argentinosaurus is long. The femoral shaft has a circumference of about at its narrowest part. Mazzetta and colleagues used regression equations to estimate its original length at , which is similar to the length of the other femur, and later in 2019 Paul gave a similar estimate of . By comparison, the complete femora preserved in the other giant titanosaurs Antarctosaurus giganteus and Patagotitan mayorum measure and , respectively. While the holotype specimen does not preserve a femur, it preserves a slender fibula (originally interpreted as a tibia) that is in length. When it was identified as a tibia, it was thought to have a comparatively short , a prominent extension at the upper front that anchored muscles for stretching the leg. However, as stated by Mazzetta and colleagues, this bone lacks both the proportions and anatomical details of a tibia, while being similar in shape to other sauropod fibulae.
Classification
Relationships within Titanosauria are amongst the least understood of all groups of dinosaurs. Traditionally, the majority of sauropod fossils from the Cretaceous had been referred to a single family, the Titanosauridae, which has been in use since 1893. In their 1993 first description of Argentinosaurus, Bonaparte and Coria noted it differed from typical titanosaurids in having hyposphene-hypantrum articulations. As these articulations were also present in the titanosaurids Andesaurus and Epachthosaurus, Bonaparte and Coria proposed a separate family for the three genera, the Andesauridae. Both families were united into a new, higher group called Titanosauria. | Argentinosaurus | Wikipedia | 355 | 584992 | https://en.wikipedia.org/wiki/Argentinosaurus | Biology and health sciences | Sauropods | Animals |
In 1997, Salgado and colleagues found Argentinosaurus to belong to Titanosauridae in an unnamed clade with Opisthocoelicaudia and an indeterminate titanosaur. In 2002, Davide Pisani and colleagues recovered Argentinosaurus as a member of Titanosauria, and again found it to be in a clade with Opisthocoelicaudia and an unnamed taxon, in addition to Lirainosaurus. A 2003 study by Jeffrey Wilson and Paul Upchurch found both Titanosauridae and Andesauridae to be invalid; the Titanosauridae because it was based on the dubious genus Titanosaurus and the Andesauridae because it was defined on plesiomorphies (primitive features) rather than on synapomorphies (newly evolved features that distinguish the group from related groups). A 2011 study by Philip Mannion and Calvo found Andesauridae to be paraphyletic (excluding some of the group's descendants) and likewise recommended its disuse.
In 2004, Upchurch and colleagues introduced a new group called Lithostrotia that included the more derived (evolved) members of Titanosauria. Argentinosaurus was classified outside this group and thus as a more basal ("primitive") titanosaurian. The basal position within Titanosauria was confirmed by a number of subsequent studies. In 2007, Calvo and colleagues named Futalognkosaurus; they found it to form a clade with Mendozasaurus and named it Lognkosauria. A 2017 study by Carballido and colleagues recovered Argentinosaurus as a member of Lognkosauria and the sister taxon of Patagotitan. In 2018, González Riga and colleagues also found it to belong in Lognkosauria, which in turn was found to belong to Lithostrotia. | Argentinosaurus | Wikipedia | 372 | 584992 | https://en.wikipedia.org/wiki/Argentinosaurus | Biology and health sciences | Sauropods | Animals |
Another 2018 study by Hesham Sallam and colleagues found two different phylogenetic positions for Argentinosaurus based on two data sets. They did not recover it as a lognkosaurian but as either a basal titanosaur or a sister taxon of the more derived Epachthosaurus. In 2019, Julian Silva Junior and colleagues found Argentinosaurus to belong to Lognkosauria once again; they recovered Lognkosauria and Rinconsauria (another group generally included in Titanosauria) to be outside Titanosauria. Another 2019 study by González Riga and colleagues also found Argentinosaurus to belong to Lognkosauria; they found this group to form a larger clade with Rinconsauria within Titanosauria, which they named Colossosauria.
Topology according to Carballido and colleagues, 2017.
Topology according to González Riga and colleagues, 2019.
Palaeobiology
The giant size of Argentinosaurus and other sauropods was likely made possible by a combination of factors; these include fast and energy-efficient feeding allowed for by the long neck and lack of mastication, fast growth and fast population recovery due to their many small offspring. Advantages of giant sizes would likely have included the ability to keep food inside the digestive tract for lengthy periods to extract a maximum of energy, and increased protection against predators. Sauropods were oviparous (egg-laying). In 2016, Mark Hallett and Matthew Wedel stated that the eggs of Argentinosaurus were probably only in volume, and that a hatched Argentinosaurus was no longer than and not heavier than . The largest sauropods increased their size by five orders of magnitude after hatching, more than in any other amniote animals. Hallett and Wedel argued size increases in the evolution of sauropods were commonly followed by size increases of their predators, theropod dinosaurs. Argentinosaurus might have been preyed on by Mapusaurus, which is among the largest theropods known. Mapusaurus is known from at least seven individuals found together, raising the possibility that this theropod hunted in packs to bring down large prey including Argentinosaurus. | Argentinosaurus | Wikipedia | 441 | 584992 | https://en.wikipedia.org/wiki/Argentinosaurus | Biology and health sciences | Sauropods | Animals |
In 2013, Sellers and colleagues used a computer model of the skeleton and muscles of Argentinosaurus to study its speed and gait. Before computer simulations, the only way of estimating speeds of dinosaurs was through studying anatomy and trackways. The computer model was based on a laser scan of a mounted skeletal reconstruction on display at the Museo Carmen Funes. Muscles and their properties were based on comparisons with living animals; the final model had a mass of . Using computer simulation and machine learning techniques, which found a combination of movements that minimised energy requirements, the digital Argentinosaurus learned to walk. The optimal gait found by the algorithms was close to a pace (forelimb and hind limb on the same side of the body move simultaneously). The model reached a top speed of just over 2 m/s (7.2 km/h, 5 mph). The authors concluded with its giant size, Argentinosaurus reached a functional limit. Much larger terrestrial vertebrates might be possible but would require different body shapes and possibly behavioural change to prevent joint collapse. The authors of the study cautioned the model is not fully realistic and too simplistic, and that it could be improved in many areas. For further studies, more data from living animals is needed to improve the soft tissue reconstruction, and the model needs to be confirmed based on more complete sauropod specimens.
Palaeoenvironment
Argentinosaurus was discovered in the Argentine Province of Neuquén. It was originally reported from the Huincul Group of the Río Limay Formation, which have since become known as the Huincul Formation and the Río Limay Subgroup, the latter of which is a subdivision of the Neuquén Group. This unit is located in the Neuquén Basin in Patagonia. The Huincul Formation is composed of yellowish and greenish sandstones of fine-to-medium grain, some of which are tuffaceous. These deposits were laid down during the Upper Cretaceous, either in the middle Cenomanian to early Turonian stages or the early Turonian to late Santonian. The deposits represent the drainage system of a braided river. | Argentinosaurus | Wikipedia | 446 | 584992 | https://en.wikipedia.org/wiki/Argentinosaurus | Biology and health sciences | Sauropods | Animals |
Fossilised pollen indicates a wide variety of plants were present in the Huincul Formation. A study of the El Zampal section of the formation found hornworts, liverworts, ferns, Selaginellales, possible Noeggerathiales, gymnosperms (including gnetophytes and conifers), and angiosperms (flowering plants), in addition to several pollen grains of unknown affinities. The Huincul Formation is among the richest Patagonian vertebrate associations, preserving fish including dipnoans and gar, chelid turtles, squamates, sphenodonts, neosuchian crocodilians, and a wide variety of dinosaurs. Vertebrates are most commonly found in the lower, and therefore older, part of the formation.
In addition to Argentinosaurus, the sauropods of the Huincul Formation are represented by another titanosaur, Choconsaurus, and several rebbachisaurids including Cathartesaura, Limaysaurus, and some unnamed species. Theropods including carcharodontosaurids such as Mapusaurus, abelisaurids including Skorpiovenator, Ilokelesia, and Tralkasaurus, noasaurids such as Huinculsaurus, paravians such as Overoraptor, and other theropods such as Aoniraptor and Gualicho have also been discovered there. Several iguanodonts are also present in the Huincul Formation. | Argentinosaurus | Wikipedia | 319 | 584992 | https://en.wikipedia.org/wiki/Argentinosaurus | Biology and health sciences | Sauropods | Animals |
Ornithischia () is an extinct clade of mainly herbivorous dinosaurs characterized by a pelvic structure superficially similar to that of birds. The name Ornithischia, or "bird-hipped", reflects this similarity and is derived from the Greek stem (), meaning "bird", and (), meaning "hip". However, birds are only distantly related to this group, as birds are theropod dinosaurs.
Ornithischians with well known anatomical adaptations include the ceratopsians or "horn-faced" dinosaurs (e.g. Triceratops), the pachycephalosaurs or "thick-headed" dinosaurs, the armored dinosaurs (Thyreophora) such as stegosaurs and ankylosaurs, and the ornithopods. There is strong evidence that certain groups of ornithischians lived in herds, often segregated by age group, with juveniles forming their own flocks separate from adults. Some were at least partially covered in filamentous (hair- or feather- like) pelts, and there is much debate over whether these filaments found in specimens of Tianyulong, Psittacosaurus, and Kulindadromeus may have been primitive feathers.
Description
Ornithischia is a very large and diverse group of dinosaurs, with members known from all continents, habitats, and a very large range of sizes. They are primarily herbivorous browsers or grazers, but some members may have also been opportunistic omnivores. Ornithischians are united by multiple features of the skull, teeth, and skeleton, including especially the presence of a and , an increased number of , the absence of , and an . Early ornithischians ranged around in length, with them increasing in size over time so that the largest armoured ornithischians were around and , the largest horned ornithischians were around and , and the largest crested ornithischians were around and . | Ornithischia | Wikipedia | 423 | 585373 | https://en.wikipedia.org/wiki/Ornithischia | Biology and health sciences | Ornitischians | Animals |
Much of the knowledge of early ornithischian anatomy comes from Lesothosaurus, which is a taxon known from multiple skulls and skeletons from the Early Jurassic of Lesotho. The rear of its skull is box-like, while the snout tapers to a point. The is small, the that opens from the side of the skull into the palate is large, shallow and triangular, the is large and round and has a palpebral creating a brow, and the lower jaw has a large .
The skulls of Emausaurus and Scelidosaurus, two early members of the armoured group Thyreophora, show similarities in the box-like skull that tapers to the front. The antorbital fossa is smaller and forming an elongate oval in both taxa, and the palpebral which is elongate and slender in Lesothosaurus is widened in Emausaurus and completely incorporated into the skull as a flat bone in Scelidosaurus. Skulls in members of the thyreophoran group Stegosauria are much longer and lower, with the width at the back being greater than the height in Stegosaurus. The snout and lower jaw are long and deep, and in some genera the does not have any teeth. As in Scelidosaurus, the palpebral forms the top border of the orbit as a flat brow bone, but the antorbital fossa is reduced to the point of absence in some genera.
Ankylosaurs, the other group of armoured ornithischians, have very robust, immobile skulls, with three significant features that separate them from other groups. The antorbital fossa, and mandibular fenestra are all closed, the sutures separating skull bones are almost completely obliterated by surface texturing, and there is bony armour above the orbits, and at the top and bottom corners of the back of the skull. Teeth are sometimes absent from the premaxilla, and both the upper and lower jaws have deeply inset teeth creating large cheeks. Ankylosaurs also have very extensive and complicated network of sinuses, formed by bone growth in the palate. | Ornithischia | Wikipedia | 448 | 585373 | https://en.wikipedia.org/wiki/Ornithischia | Biology and health sciences | Ornitischians | Animals |
The skulls are known from many early ornithopods and some heterodontosaurids, showing similar general features. Skulls are relatively tall with shorter snouts, but the snout is elongated in some later taxa like Thescelosaurus. The orbit and antorbital fossa are large, but the nasal opening is small, and while teeth are present in the premaxilla, there is a toothless front tip that likely formed a keratinous beak. The premaxillary teeth and the first lower tooth in Heterodontosaurus are enlarged into sizeable canines. In later ornithopods, the skulls are more elongate and sometimes fully rectangular, with a very large nasal opening, and a thin, elongate palpebral that can extend the entire way across the orbit. Teeth are almost always absent from the premaxilla, the antorbital fossa is reduced and round to slit-like, the tip of the snout is sometimes flared to form a broad beak. Members of the ornithopod family Hadrosauridae show further adaptations, including the formation of where teeth are continuously replaced, and in many genera the development of prominent cranial crests formed by multiple different bones of the skull.
Pachycephalosauria, at one time thought to be close to ornithopods and now known to be related instead to ceratopsians, show a unique skull anatomy that is unlike any other ornithischian. The bones of the top of the skull are thickened and in many taxa expanded significantly to form round bony domes as the top of the head, as well as possessing small nodes or elongate spikes along the back edge of the skull. Many taxa are only known from these thick skull domes, which are fused from the and bones. As in many other ornithischians, the snout is short and tapering, the nasal opening is small, the antorbital fossa is sometimes absent, and there are premaxillary teeth, though only three. The two palpebrals are also incorporated into the skull roof as in thyreophorans, rather than free. | Ornithischia | Wikipedia | 449 | 585373 | https://en.wikipedia.org/wiki/Ornithischia | Biology and health sciences | Ornitischians | Animals |
Ceratopsians, the sister group to pachycephalosaurs, also display many cranial adaptations, most importantly the evolution of a bone called the that forms the top beak opposite the predentary. The bones flare to the sides to create a pentagonal skull seen from above, the nasal opening is closer to the top of the snout than the teeth, and while the snout tapers in some taxa, it is very deep and short in Psittacosaurus. The ceratopsian palpebral is generally triangular, and the back edge of the skull roof forms a flat frill that is enlarged in more derived ceratopsians. The ceratopsian family Ceratopsidae progresses on these features with the addition of horns above each orbit and on the top of the snout, as well as substantial elongation of the frill and in many genera the development of two large forming holes in the frill. The skull and frill elongation makes the skulls of Torosaurus and Pentaceratops the largest of any known terrestrial vertebrate, at over long.
Early ornithischians were relatively small dinosaurs, averaging about 1–2 meters in body length, with a triangular skull that had large circular orbits on the sides. This suggests that early ornithischians had relatively huge eyes that faced laterally. The forelimbs of early ornithischians are considerably shorter than their hindlimbs. A small forelimb such as those present in early ornithischians would not have been useful for locomotion, and it is evident that early ornithischians were bipedal dinosaurs. The entire skeleton was lightly built, with a largely fenestrated skull and a very stout neck and trunk. The tail is nearly half of the dinosaurs' overall length. The long tail presumably acted as a counterbalance and as a compensating mechanism for shifts in the creature's center of gravity. The hindlimbs of early ornithischians show that the tibia is considerably longer than the femur, a feature that suggests that early ornithischians were adapted for bipedality, and were fast runners. | Ornithischia | Wikipedia | 448 | 585373 | https://en.wikipedia.org/wiki/Ornithischia | Biology and health sciences | Ornitischians | Animals |
"Bird-hip"
The ornithischian pelvis was "opisthopubic", meaning that the pubis pointed down and backwards (posterior), parallel with the ischium (Figure 1a). Additionally, the ilium had a forward-pointing process (the preacetabular process) to support the abdomen. This resulted in a four-pronged pelvic structure. In contrast to this, the saurischian pelvis was "propubic", meaning the pubis pointed toward the head (anterior), as in ancestral reptiles (Figure 1b).
The opisthopubic pelvis independently evolved at least three times in dinosaurs (in ornithischians, birds and therizinosauroids). Some argue that the opisthopubic pelvis evolved a fourth time, in the clade Dromaeosauridae, but this is controversial, as other authors argue that dromaeosaurids are mesopubic. It has also been argued that the opisthopubic condition is basal to maniraptorans (including among others birds, therizinosauroids and dromaeosaurids), with some clades having later experienced a reversal to the propubic condition.
Classification
History | Ornithischia | Wikipedia | 263 | 585373 | https://en.wikipedia.org/wiki/Ornithischia | Biology and health sciences | Ornitischians | Animals |
The first recognition of an herbivorous group of dinosaurs was named Orthopoda in 1866 by Edward Drinker Cope, a name that is now recognized as a synonym of Ornithischia. Discussions on the taxonomy of dinosaurs by Othniel Charles Marsh identified two major groups of herbivorous dinosaurs, Ornithopoda and Stegosauria, containing genera from a broad geographic and stratigraphic distribution. While often these groups were placed within Dinosauria, Harry Govier Seeley suggested instead in 1888 that ornithopods and stegosaurs, which shared many features in the skull, limbs, and hip, were unrelated to other dinosaurs, and so he proposed that Dinosauria was an unnatural grouping of two independently-evolved suborders, Saurischia and Ornithischia. It is from the anatomy of the hip that Seeley chose the name Ornithischia, referencing the bird-like anatomy of the ischium bone. Many researchers did not follow the division of Seeley at first, with Marsh naming the group Predentata to unite ornithopods, stegosaurs, and Ceratopsia within Dinosauria, but with additional work and new discoveries the unnatural nature of Dinosauria came to be accepted, and the names Seeley proposed found common use. After further decades, in 1974 Robert T. Bakker and Peter M. Galton provided new evidence in support of the grouping of ornithischians and saurischians together within a natural Dinosauria, which has been supported since. | Ornithischia | Wikipedia | 321 | 585373 | https://en.wikipedia.org/wiki/Ornithischia | Biology and health sciences | Ornitischians | Animals |
The first cladistic studies on Ornithischia were published simultaneously in 1984 by David B. Norman, Andrew R. Milner, and Paul C. Sereno. These studies differed somewhat in their results, but found that Iguanodon was closer to hadrosaurs than other ornithopods, followed by Dryosaurus, Hypsilophodon and then Lesothosaurus and its relatives. While the study of Norman placed ceratopsians between Hypsilophodon and more derived ornithopods, the study of Sereno placed ceratopsians with ankylosaurs and stegosaurs. It has since been recognized by that ceratopsians are closer to ornithopods than the armoured ankylosaurs and stegosaurs, but the relationships of some groups are still in states of change, with some more consistent results than others. An early study that looked at the relationships within Ornithischia with greater detail was that of Sereno in 1986, who provided features that supported the evolution of all ornithischian groups and shared similarities with earlier studies. Sereno found that Lesothosaurus was the most primitive ornithischian, with all other ornithischians united within the clade Genasauria, which has two subgroups. The first subgroup, Thyreophora, unites ankylosaurs and stegosaurs along with more primitive taxa like Scelidosaurus, while the second subgroup, Cerapoda, contained ornithopods, ceratopsians, pachycephalosaurs, and small primitive forms. One group of the small primitive forms considered to be cerapodans by Sereno, Heterodontosauridae, has since been found to be a group of very early ornithischians of similar evolutionary status as Lesothosaurus, although this result is not definitive. | Ornithischia | Wikipedia | 397 | 585373 | https://en.wikipedia.org/wiki/Ornithischia | Biology and health sciences | Ornitischians | Animals |
The first large-scale numerical analysis of the phylogenetics of Ornithischia was published in 2008 by Richard J. Butler and colleagues, including many primitive ornithischians and members from all of the major subgroups, to test some of the hypotheses given previously about ornithischian evolution and the relationships of the groups. Thyreophora was found to be a supported group, as well as the clade of pachycephalosaurs and ceratopsians that Sereno named Marginocephalia in 1986. Some taxa considered earlier to be ornithopods, like heterodontosaurids, Agilisaurus, Hexinlusaurus and Othnielia, were instead found to be outside of both Ornithopoda and Ceratopsia, but still closer to those two groups than thyreophorans. The early Argentinian taxon Pisanosaurus was found to be the most primitive ornithischian, but while overall results agreed with earlier studies and showed some stability, areas of the evolutionary tree were found to be problematic, and with potential for later change. In 2021, a new phylogenetic study was published authored by Paul-Emile Dieudonné and colleagues that instead found Heterodontosauridae to nest alongside Pachycephalosauria within Marginocephalia, changing the early evolution of ornithopods considerably, and showing that the evolution of ornithischians was far from definitive. Below are the cladograms of Sereno, Butler and colleagues, and Dieudonné and colleagues, restricted to the major clades of Ornithischia, Heterodontosauridae, Lesothosaurus and Pisanosaurus.
Sereno, 1986
Butler et al., 2008
Dieudonné et al., 2021 | Ornithischia | Wikipedia | 374 | 585373 | https://en.wikipedia.org/wiki/Ornithischia | Biology and health sciences | Ornitischians | Animals |
When Ornithischia was first named, Seeley united the orders Ornithopoda and Stegosauria of Marsh's taxonomy within the new group. Ceratopsia was then recognized as a unique group related to ornithopods and stegosaurs by Marsh by 1894, with each of the three suborders still being recognized as distinct groups today. Ceratopsians are recognized as group that grew in diversity later in the Cretaceous after evolving in the Late Jurassic, encompassing a diverse array of bodyforms from the small, bipedal Psittacosaurus up to the very large, quadrupedal, horned and frilled ceratopsids like Torosaurus, which has the longest skull of any terrestrial vertebrate. Ornithopods, which range from the Early Jurassic in some studies until the end of the Cretaceous with continuous diversity, are generally bipedal and unarmoured, though some later groups like Hadrosauridae evolved complex dental anatomy in the form of batteries of teeth. Stegosaurs are comparatively limited, restricted to a primarily Jurassic group of moderate to large, quadrupedal herbivores with two rows of vertical plates ornamenting their spine, which possibly did not go extinct until the Late Cretaceous, though at the time of Marsh Stegosauria was used for all armored and quadrupedal taxa, many of which are now separated into Ankylosauria. Ankylosaurs were only recognized as a distinct group from stegosaurs in the 1920s despite many members being known for decades before, with the group now encompassing a broad array of heavy, quadrupedal ornithischians with extensive armour covering their body and skull. The fifth recognized major subgroup of ornithischians is Pachycephalosauria, which was first named in 1974 after being confused for a long time with the theropod Troodon on account of their similarly omnivorous and unique teeth. Pachycephalosaurians are unique for their tall, thickened skulls and small, bipedal bauplan, suggesting that their domes were for sexual display or combat in the form of head-butting or flank-butting | Ornithischia | Wikipedia | 455 | 585373 | https://en.wikipedia.org/wiki/Ornithischia | Biology and health sciences | Ornitischians | Animals |
Some taxa, particularly those at one point groupt together in the ornithopod family Hypsilophodontidae, are now recognized to not fall within any of the major ornithischian groups, and either be outside Genasauria, or on the basal stem of Neornithischia outside Cerapoda | Ornithischia | Wikipedia | 69 | 585373 | https://en.wikipedia.org/wiki/Ornithischia | Biology and health sciences | Ornitischians | Animals |
Following the publication of the PhyloCode to provide rules and regulations on the use of taxonomic names for groups, the internal classification of Ornithischia was revised by Daniel Madzia and colleagues in 2021 to provide a framework of definitions and taxa for other studies to follow and modify from. They names the new clade Saphornithischia to unite heterodontosaurids with more derived ornithischians to encompass the concept of the well-supported clear ornithischians, as the origins of the group and the relationships of primitive taxa like Pisanosaurus and members of Silesauridae may sometimes be found to be ornithischians outside this core grouping. Madzia and colleagues also provided a composite cladogram of Ornithischia to illustrate the consensus of internal divisions, which can be seen below. Ornithischia has been defined as all taxa closer to Iguanodon than Allosaurus or Camarasaurus. Genasauria has been defined as the smallest clade containing Ankylosaurus, Iguanodon, Stegosaurus, and Triceratops.
Multiple taxa within Ornithischia fall around the origin of the group, or cannot be classified definitively. Lesothosaurus and Laquintasaura have been found as basal thyreophorans or basal ornithischians, Chilesaurus is either a theropod or a basal ornithischian, Pisanosaurus has been found as a basal ornithischian or a non-ornithischian silesaurid, Eocursor has been a basal ornithischian or a basal member of Neornithischia, Serendipaceratops cannot be classified beyond Ornithischia as it is either an ankylosaur or a ceratopsian, and Alocodon, Fabrosaurus, Ferganocephale, Gongbusaurus, Taveirosaurus, Trimucrodon and Xiaosaurus are dubious ornithischians of uncertain basal classification. Depending on the phylogenetic results, Silesauridae could either be a clade within Ornithischia, its members could form an evolutionary gradient, or some members found form a clade while others are part of a gradient.
Evolution | Ornithischia | Wikipedia | 465 | 585373 | https://en.wikipedia.org/wiki/Ornithischia | Biology and health sciences | Ornitischians | Animals |
For a long time, the only understanding of the origins of Ornithischia came from Lesothosaurus and Pisanosaurus, which together represented the best-known Early Jurassic and Triassic ornithischians respectively. Many suggestions of taxa and specimens that could be referred to Ornithischia from the Triassic were based on teeth and jaw bones, as they showed similar adaptations for herbivory. The genera Revueltosaurus, Galtonia, Pekinosaurus, Tecovasaurus, Lucianosaurus, Protecovasaurus, Crosbysaurus, and Azendohsaurus were all at one time considered to be Triassic ornithischians with only their teeth known, but are now recognized to be completely unrelated. The only early ornithischians that were considered to be diagnostic in a 2004 review by Norman and colleagues were Lesothosaurus, Pisanosaurus and Technosaurus, limiting the early ornithischian record to only two Triassic genera from Argentina and the United States and one Early Jurassic genus from South Africa, with all the tooth taxa being considered undiagnostic. Referrals of isolated teeth to Ornithischia based on herbivorous features began to be extensively questioned by William G. Parker and colleagues in 2005 after the discovery of skull and skeleton material clearly from Revueltosaurus showing that the "ornithischian-like" teeth were from an animal more closely related to crocodiles than birds, and there were multiple occurrences of herbivory throughout Triassic reptiles. Removing the list of Triassic tooth taxa from Ornithischia, the early diversity of the group was substantially reduced, especially in comparison to the known Triassic diversity of theropods and sauropodomorphs. If Pisanosaurus represented the earliest ornithischian, there would be at least a 20 million year gap in the evolution of Ornithischia until Lesothosaurus and heterodontosaurids. It is possible that the limited early record of ornithischians is due to them inhabiting environments that were less conducive to fossilization, or that the phylogenetics of the group were incorrect and that early ornithischians were already known but identified as members of other groups. | Ornithischia | Wikipedia | 454 | 585373 | https://en.wikipedia.org/wiki/Ornithischia | Biology and health sciences | Ornitischians | Animals |
First noted in the 2003 naming of the early taxon Silesaurus, some taxa generally considered non-dinosaurs show similarities to ornithischians in the teeth and jaw anatomy. These basal taxa, which were then grouped within Silesauridae and commonly as the sister group to Dinosauria, may instead be the earliest ornithischians. They show adaptations for the evolution of herbivory, and can fill in the gap in early evolution of ornithischians that were otherwise only clearly known since the beginning of the Jurassic. This hypothesis has found support in multiple different phylogenetic analyses, but the results are not yet accepted as definitive enough to contradict other possible evolutionary strategies of dinosaurs. Alternatively, and more in line with earlier studies on dinosaur evolution, silesaurids may be the sister taxa to the Saurischia-Ornithischia split, or even other arrangements of the three main dinosaur groups Ornithischia, Sauropodomorpha, and Theropoda. The 2017 phylogenetic study of Matthew G. Baron and colleagues suggested that instead of a Saurischia-Ornithischia split, ornithischians were instead closest to theropods in the clade Ornithoscelida, with sauropodomorphs being outside the grouping. Under this case, the omnivory in the earliest sauropodomorphs and ornithischians would be the ancestral condition for dinosaurs, along with the grasping abilities seen in the earliest ornithischians and theropods. While Ornithoscelida is a possible hypothesis for the evolution of dinosaurs and the close relationships of Ornithischia, follow-up studies have not found it statistically more likely than the traditional dichotomy of Ornithischia and Saurischia, or the third alternative, Phytodinosauria, where ornithischians and sauropodomorphs are closer to each other than theropods. | Ornithischia | Wikipedia | 410 | 585373 | https://en.wikipedia.org/wiki/Ornithischia | Biology and health sciences | Ornitischians | Animals |
Along with Pisanosaurus, which was supported as the earliest ornithischian for a time before being considered just as likely to be a silesaur rather than an ornithischian, an additional problematic taxon is Chilesaurus from the Late Jurassic of Chile. While it was originally named as a derived theropod with unique anatomy, it was found in studies based on Baron and colleagues results to instead be either the basalmost ornithischian, or a sauropodomorph. As the earliest ornithischian, Chilesaurus tied multiple details of ornithischian and theropod anatomy together supporting their union in Ornithoscelida, though when it is not the basalmost ornithischian, a traditional Saurischia is recovered. The problematic nature of Chilesaurus requires further revisiting of its anatomy, but the details of vertebral air pockets, pelvis shape, and hand support it as a theropod. Daemonosaurus, typically a theropod or close relative of herrerasaurs, has also been found as the basalmost ornithischian at times when Ornithoscelida is recovered, but it does not share any unique features with ornithischians and redescribing its anatomy found it fairly confidently to be a basal dinosaur not related closely to Ornithischia.
The phylogenetic analysis of Norman and colleagues in 2022 recovered the members of Silesauridae as forming an ancestral grade within Ornithischia even with the inclusion of Chilesaurus, supporting the earlier results of Müller and Garcia and their evolutionary trends for early ornithischian anatomy. Norman and colleagues used Prionodontia over both Saphornithischia and Genasauria, since all were recovered as encompassing the same node. The earliest ornithischians under this reconstruction were faunivorous, as seen by Lewisuchus, which has typical teeth like theropods. Serrations on teeth become larger for taxa more derived than Asilisaurus, the development of a cingulum in teeth is seen in Technosaurus and later ornithischians, the lower jaw becomes more elongate in taxa above Silesaurus, and core ornithischians are united by the pubic bone angling backwards, and the modification of the ankle joint. | Ornithischia | Wikipedia | 483 | 585373 | https://en.wikipedia.org/wiki/Ornithischia | Biology and health sciences | Ornitischians | Animals |
Palaeoecology
Ornithischians shifted from bipedal to quadrupedal posture at least three times in their evolutionary history and it has been shown primitive members may have been capable of both forms of movement.
Most ornithischians were herbivorous. In fact, most of the unifying characters of Ornithischia are thought to be related to this herbivory. For example, the shift to an opisthopubic pelvis is thought to be related to the development of a large stomach or stomachs and gut which would allow ornithischians to more effectively digest plant matter. The smallest known ornithischian is Fruitadens haagarorum. The largest Fruitadens individuals reached just 65–75 cm. Previously, only carnivorous, saurischian theropods were known to reach such small sizes. At the other end of the spectrum, the largest known ornithischians reach about 15 meters (smaller than the largest saurischians).
However, not all ornithischians were strictly herbivorous. Some groups, like the heterodontosaurids, were likely omnivores. At least one species of ankylosaurian, Liaoningosaurus paradoxus, appears to have been at least partially carnivorous, with hooked claws, fork-like teeth, and stomach contents suggesting that it may have fed on fish. The members of Genasauria were primarily herbivores. Genasaurians most often had their head at the level of one meter, which suggests they were feeding primarily on “ground-level plants such as ferns, cycads, and other herbaceous gymnosperms."
There is strong evidence that some ornithischians lived in herds. This evidence consists of multiple bone beds where large numbers of individuals of the same species and of different age groups died simultaneously. | Ornithischia | Wikipedia | 389 | 585373 | https://en.wikipedia.org/wiki/Ornithischia | Biology and health sciences | Ornitischians | Animals |
Pulmonology (, , from Latin pulmō, -ōnis "lung" and the Greek suffix "study of"), pneumology (, built on Greek πνεύμων "lung") or pneumonology () is a medical specialty that deals with diseases involving the respiratory tract. It is also known as respirology, respiratory medicine, or chest medicine in some countries and areas.
Pulmonology is considered a branch of internal medicine, and is related to intensive care medicine. Pulmonology often involves managing patients who need life support and mechanical ventilation. Pulmonologists are specially trained in diseases and conditions of the chest, particularly pneumonia, asthma, tuberculosis, emphysema, and complicated chest infections.
Pulmonology/respirology departments work especially closely with certain other specialties: cardiothoracic surgery departments and cardiology departments.
Journals of pulmonology
American Association for Respiratory Care
American College of Chest Physicians
American Lung Association
American Thoracic Society
British Thoracic Society
European Respiratory Society
History of pulmonology
One of the first major discoveries relevant to the field of pulmonology was the discovery of pulmonary circulation. Originally, it was thought that blood reaching the right side of the heart passed through small 'pores' in the septum into the left side to be oxygenated, as theorized by Galen; however, the discovery of pulmonary circulation disproves this theory, which had previously been accepted since the 2nd century. Thirteenth-century anatomist and physiologist Ibn Al-Nafis accurately theorized that there was no 'direct' passage between the two sides (ventricles) of the heart. He believed that the blood must have passed through the pulmonary artery, through the lungs, and back into the heart to be pumped around the body. This is believed by many to be the first scientific description of pulmonary circulation.
Although pulmonary medicine only began to evolve as a medical specialty in the 1950s, William Welch and William Osler founded the 'parent' organization of the American Thoracic Society, the National Association for the Study and Prevention of Tuberculosis. The care, treatment, and study of tuberculosis of the lung is recognised as a discipline in its own right, phthisiology. When the specialty did begin to evolve, several discoveries were being made linking the respiratory system and the measurement of arterial blood gases, attracting more and more physicians and researchers to the developing field. | Pulmonology | Wikipedia | 509 | 585383 | https://en.wikipedia.org/wiki/Pulmonology | Biology and health sciences | Fields of medicine | null |
Pulmonology and its relevance in other medical fields
Surgery of the respiratory tract is generally performed by specialists in cardiothoracic surgery (or thoracic surgery), though minor procedures may be performed by pulmonologists. Pulmonology is closely related to critical care medicine when dealing with patients who require mechanical ventilation. As a result, many pulmonologists are certified to practice critical care medicine in addition to pulmonary medicine. There are fellowship programs that allow physicians to become board certified in pulmonary and critical care medicine simultaneously. Interventional pulmonology is a relatively new field within pulmonary medicine that deals with the use of procedures such as bronchoscopy and pleuroscopy to treat several pulmonary diseases. Interventional pulmonology is increasingly recognized as a specific medical specialty.
Diagnosis
The pulmonologist begins the diagnostic process with a general review focusing on:
hereditary diseases affecting the lungs (cystic fibrosis, alpha 1-antitrypsin deficiency)
exposure to toxicants (tobacco smoke, asbestos, exhaust fumes, coal mining fumes, e-cigarette aerosol,)
exposure to infectious agents (certain types of birds, malt processing)
an autoimmune diathesis that might predispose to certain conditions (pulmonary fibrosis, pulmonary hypertension)
Physical diagnostics are as important as in other fields of medicine.
Inspection of the hands for signs of cyanosis or clubbing, chest wall, and respiratory rate.
Palpation of the cervical lymph nodes, trachea and chest wall movement.
Percussion of the lung fields for dullness or hyper-resonance.
Auscultation (with a stethoscope) of the lung fields for diminished or unusual breath sounds.
Rales or rhonchi heard over lung fields with a stethoscope.
As many heart diseases can give pulmonary signs, a thorough cardiac investigation is usually included.
Procedures | Pulmonology | Wikipedia | 390 | 585383 | https://en.wikipedia.org/wiki/Pulmonology | Biology and health sciences | Fields of medicine | null |
Clinical procedures
Pulmonary clinical procedures include the following pulmonary tests and procedures:
Medical laboratory investigation of blood (blood tests). Sometimes arterial blood gas tests are also required.
Spirometry the determination of maximum airflow at a given lung volume as measured by breathing into a dedicated machine; this is the key test to diagnose airflow obstruction.
Pulmonary function testing including spirometry, as above, plus response to bronchodilators, lung volumes, and diffusion capacity, the latter being a measure of lung oxygen absorptive area
Bronchoscopy with bronchoalveolar lavage (BAL), endobronchial and transbronchial biopsy and epithelial brushing
Chest X-rays
CT scan
Scintigraphy and other methods of nuclear medicine
Positron emission tomography (especially in lung cancer)
Polysomnography (sleep studies) commonly used for the diagnosis of sleep apnea
Surgical procedures
Major surgical procedures on the heart and lungs are performed by a thoracic surgeon. Pulmonologists often perform specialized procedures to get samples from the inside of the chest or inside of the lung. They use radiographic techniques to view vasculature of the lungs and heart to assist with diagnosis.
Treatment and therapeutics
Medication is the most important treatment of most diseases of pulmonology, either by inhalation (bronchodilators and steroids) or in oral form (antibiotics, leukotriene antagonists). A common example being the usage of inhalers in the treatment of inflammatory lung conditions such as asthma or chronic obstructive pulmonary disease. Oxygen therapy is often necessary in severe respiratory disease (emphysema and pulmonary fibrosis). When this is insufficient, the patient might require mechanical ventilation. | Pulmonology | Wikipedia | 361 | 585383 | https://en.wikipedia.org/wiki/Pulmonology | Biology and health sciences | Fields of medicine | null |
Pulmonary rehabilitation has been defined as a multidimensional continuum of services directed to persons with pulmonary disease and their families, usually by an interdisciplinary team of specialists, with the goal of achieving and maintaining the individual's maximum level of independence and functioning in the community. Pulmonary rehabilitation is intended to educate the patient, the family, and improve the overall quality of life and prognosis for the patient. Interventions can include exercise, education, emotional support, oxygen, noninvasive mechanical ventilation, optimization of airway secretion clearance, promoting compliance with medical care to reduce numbers of exacerbations and hospitalizations, and returning to work and/or a more active and emotionally satisfying life. These goals are appropriate for any patients with diminished respiratory reserve whether due to obstructive or intrinsic pulmonary diseases (oxygenation impairment) or neuromuscular weakness (ventilatory impairment). A pulmonary rehabilitation team may include a rehabilitation physician, a pulmonary medicine specialist, physician assistant and allied health professionals including a rehabilitation nurse, a respiratory therapist, a speech-language pathologist, a physical therapist, an occupational therapist, a psychologist, and a social worker among others. Additionally, breathing games are used to motivate children to perform pulmonary rehabilitation.
Education and training
Pulmonologist
In the United States, pulmonologists are physicians who, after receiving a medical degree (MD or DO), complete residency training in internal medicine, followed by at least two additional years of subspeciality fellowship training in pulmonology. After satisfactorily completing a fellowship in pulmonary medicine, the physician is permitted to take the board certification examination in pulmonary medicine. After passing this exam, the physician is then board certified as a pulmonologist. Most pulmonologists complete three years of combined subspecialty fellowship training in pulmonary medicine and critical care medicine.
Pediatric pulmonologist
In the United States, pediatric pulmonologists are physicians who, after receiving a medical degree (MD, DO, MBBS, MBBCh, etc.), complete residency training in pediatrics, followed by at least three additional years of subspeciality fellowship training in pulmonology. Pediatric pulmonologists treat diseases of the airways, lungs, respiratory mechanics and aerodigestive system. | Pulmonology | Wikipedia | 466 | 585383 | https://en.wikipedia.org/wiki/Pulmonology | Biology and health sciences | Fields of medicine | null |
Scientific research
Pulmonologists are involved in both clinical and basic research of the respiratory system, ranging from the anatomy of the respiratory epithelium to the most effective treatment of pulmonary hypertension. Scientific research also takes place to look for causes and possible treatment in diseases such as pulmonary tuberculosis and lung cancer. | Pulmonology | Wikipedia | 62 | 585383 | https://en.wikipedia.org/wiki/Pulmonology | Biology and health sciences | Fields of medicine | null |
The cherimoya (Annona cherimola), also spelled chirimoya and called chirimuya by the Quechua people, is a species of edible fruit-bearing plant in the genus Annona, from the family Annonaceae, which includes the closely related sweetsop and soursop. The plant has long been believed to be native to Ecuador and Peru, with cultivation practised in the Andes and Central America, although a recent hypothesis postulates Central America as the origin instead, because many of the plant's wild relatives occur in this area.
Cherimoya is grown in tropical and subtropical regions throughout the world including Central America, northern South America, Southern California, South Asia, Australia, the Mediterranean region, and North Africa. American writer Mark Twain called the cherimoya "the most delicious fruit known to men". The creamy texture of the flesh gives the fruit its secondary name, the custard apple.
Etymology
The name is derived from the Quechua word , which means "cold seeds". The plant grows at high altitudes, where the weather is colder, and the seeds will germinate at higher altitudes. In Bolivia, Chile, Colombia, Ecuador, Peru, and Venezuela, the fruit is commonly known as chirimoya (spelled according to the rules of the Spanish language).
Description
Annona cherimola is a fairly dense, fast-growing, woody,
briefly deciduous
but mostly evergreen, low-branched, spreading tree
or shrub, tall.
Mature branches are sappy and woody. Young branches and twigs have a matting of short, fine, rust-colored hairs. The leathery leaves are long wide, and mostly elliptic, pointed at the ends and rounded near the leaf stalk. When young, they are covered with soft, fine, tangled, rust-colored hairs. When mature, the leaves bear hairs only along the veins on the undersurface. The tops are hairless and a dull medium green with paler veins, the backs are velvety, dull grey-green with raised pale green veins. New leaves are whitish below.
Leaves are single and alternate, dark green, and slightly hairy on the top surface. They attach to branches with stout long and densely hairy leaf stalks. | Cherimoya | Wikipedia | 449 | 585460 | https://en.wikipedia.org/wiki/Cherimoya | Biology and health sciences | Other culinary fruits | Plants |
Cherimoya trees bear very pale green, fleshy flowers. They are long with a very strong, fruity odor. Each flower has three outer, greenish, fleshy, oblong, downy petals and three smaller, pinkish inner petals with yellow or brown, finely matted hairs outside, whitish with purple spots and many stamens on the inside. Flowers appear on the branches opposite to the leaves, solitary or in pairs or groups of three, on flower stalks that are covered densely with fine rust-colored hairs, long. Buds are long and wide at the base. The pollen is shed as permanent tetrads.
Fruits
The edible cherimoya fruit is a large, green, conical or heart-shaped compound fruit, long, with diameters of , and skin that gives the appearance of having overlapping scales or knobby warts. They ripen to brown with a fissured surface in late winter and early spring; they weigh on the average , but extra-large specimens may weigh or more.
Cherimoya fruits are commercially classified according to degree of surface irregularity, as follows: 'Lisa', almost smooth, difficult to discern areoles; 'Impresa', with "fingerprint" depressions; 'Umbonata', with rounded protrusions at the apex of each areole; 'Mamilata' with fleshy, nipple-like protrusions; or 'Tuberculata', with conical protrusions having wart-like tips.
The flesh of the cherimoya contains numerous hard, inedible, black, bean-like, glossy seeds, long and about half as wide. Cherimoya seeds are poisonous if crushed open. Like other members of the family Annonaceae, the entire plant contains small amounts of neurotoxic acetogenins, such as annonacin, which appear to be linked to atypical parkinsonism in Guadeloupe. Moreover, an extract of the bark can induce paralysis if injected.
Distribution and habitat | Cherimoya | Wikipedia | 414 | 585460 | https://en.wikipedia.org/wiki/Cherimoya | Biology and health sciences | Other culinary fruits | Plants |
Widely cultivated now, A. cherimola is believed to have originated in the Andes of South America at altitudes of , although an alternative hypothesis postulates Central America as the origin, instead, because many of the plant's wild relatives occur in this area. From there it was taken by Europeans to various parts of the tropics. Unlike other Annona species, A. cherimola has not successfully naturalized in West Africa, and Annona glabra is often misidentified as this species in Australasia.
Native
Neotropic:
Western South America: Ecuador, Peru
Current (naturalized and native)
Neotropic:
Caribbean: Florida, Cuba, Dominican Republic, Haiti, Jamaica, Puerto Rico
Central America: Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Panama
Northern South America: Guyana, Venezuela
Southern North America: Mexico
Western South America: Bolivia, Colombia, Ecuador, Peru
Southern South America: Chile, Brazil
Palearctic: Algeria, Egypt, Libya, France, Italy, Spain, Madeira, Azores
Afrotropic: Eritrea, Somalia, Tanzania,
Indomalaya: India, Singapore, Thailand
Australia
A. cherimola is not native to Chile. When it was introduced is unknown, but it happened likely in pre-Hispanic times. Traditionally, it has been cultivated in the valleys and oases of the north, as far south as the valley of Aconcagua.
Ecology
Pollination
The flowers of A. cherimola are hermaphroditic and have a mechanism to avoid self-pollination. The short-lived flowers open as female, then progress to a later, male stage in a matter of hours. This requires a separate pollinator that not only can collect the pollen from flowers in the male stage, but also deposit it in flowers in the female stage. Studies of which insect(s) serve as the natural pollinator in the cherimoya's native region have been inconclusive; some form of beetle is suspected. | Cherimoya | Wikipedia | 405 | 585460 | https://en.wikipedia.org/wiki/Cherimoya | Biology and health sciences | Other culinary fruits | Plants |
Quite often, the female flower is receptive in the early part of the first day, but pollen is not produced in the male stage until the late afternoon of the second day. Honey bees are not good pollinators of this plant, for example, because their bodies are too large to fit between the fleshy petals of the female flower. Female flowers have the petals only partially separated, and the petals separate widely when they become male flowers. So, the bees pick up pollen from the male flowers, but are unable to transfer this pollen to the female flowers. The small beetles which are suspected to pollinate cherimoya in its land of origin must therefore be much smaller than bees.
For fruit production outside the cherimoya's native region, cultivators must either rely upon the wind to spread pollen in dense orchards or else use hand pollination. Pollinating by hand requires a paint brush. Briefly, to increase fruit production, growers collect the pollen from the male plants with the brush, and then transfer it to the female flowers immediately or store it in the refrigerator overnight. Cherimoya pollen has a short life, but it can be extended with refrigeration.
Climate requirements
The evaluation of 20 locations in Loja Province, Ecuador, indicated certain growing preferences of wild cherimoya, including altitude between , optimum annual temperature range between , annual precipitation between , and soils with high sand content and slightly acidic properties with pH between 5.0 and 6.5.
In Western horticulture, growers are often advised to grow cherimoya in full sun, while the plant has been considered shade-tolerant in Japan. In 2001, a study conducted by Kyoto University showed shading of 50–70% sunlight was adequate to obtain an optimal light environment.
Cultivation
Cultivars | Cherimoya | Wikipedia | 362 | 585460 | https://en.wikipedia.org/wiki/Cherimoya | Biology and health sciences | Other culinary fruits | Plants |
The cherimoya of the Granada-Málaga tropical coast in Spain is a fruit of the cultivar 'Fino de Jete' with the EU's protected designation of origin appellation. 'Fino de Jete' fruits have skin type Impressa and are smooth or slightly concave at the edges. The fruit is round, oval, heart-shaped, or kidney-shaped. The seeds are enclosed in the carpels and so do not detach easily. The flavor balances intense sweetness with slight acidity and the soluble sugar content exceeds 17° Bx. This variety is prepared and packed in the geographical area because "it is a very delicate perishable fruit and its skin is very susceptible to browning caused by mechanical damage, such as rubbing, knocks, etc. The fruit must be handled with extreme care, from picking by hand in the field to packing in the warehouse, which must be carried out within 24 hours. Repacking or further handling is strictly forbidden."
Annona cherimola, preferring the cool Andean altitudes, readily hybridizes with other Annona species. A hybrid with A. squamosa called atemoya has received some attention in West Africa, Australia, Brazil, and Florida.
Propagation
The tree thrives throughout the tropics at altitudes of . Though sensitive to frost, it must have periods of cool temperatures or the tree will gradually go dormant. The indigenous inhabitants of the Andes say the cherimoya cannot tolerate snow.
In the Mediterranean region, it is cultivated mainly in southern Spain and Portugal, where it was introduced between 1751 and 1797, after which it was carried to Italy, but now can also be found in several countries of Africa, the Middle East, and Oceania. It is cultivated throughout the Americas, including Hawaii since 1790 and California, where it was introduced in 1871.
Harvest
Large fruits which are uniformly green, without cracks or mostly browned skin, are best. The optimum temperature for storage is , depending on cultivar, ripeness stage, and duration, with an optimum relative humidity of 90–95%. Unripe cherimoyas will ripen at room temperature, when they will yield to gentle pressure. Exposure to ethylene (100 ppm for one to two days) accelerates ripening of mature green cherimoya and other Annona fruits; they can ripen in about five days if kept at . Ethylene removal can also be helpful in slowing the ripening of mature green fruits.
Nutrition and edibility | Cherimoya | Wikipedia | 509 | 585460 | https://en.wikipedia.org/wiki/Cherimoya | Biology and health sciences | Other culinary fruits | Plants |
Raw cherimoya fruit is 79% water, 18% carbohydrate, 2% protein, and 1% fat (table). In a 100-gram reference amount providing 75 calories, cherimoya is a rich source (20% or more of the Daily Value, DV) of vitamin B6 and a moderate source (10–19% DV) of vitamin C, dietary fiber, and riboflavin (table).
"The pineapple, the mangosteen, and the cherimoya", wrote the botanist Berthold Carl Seemann, "are considered the finest fruits in the world, and I have tasted them in those localities where they are supposed to attain their highest perfection – the pineapple in Guayaquil, the mangosteen in the Indian Archipelago, and the cherimoya on the slopes of the Andes, and if I were asked which would be the best fruit, I would choose without hesitation, cherimoya. Its taste, indeed, surpasses that of every other fruit, and Haenke was quite right when he called it the masterpiece of Nature."
Fruits require storage at to inhibit softening and maintain edibility. Different varieties have different flavors, textures, and shapes. The flavor of the flesh ranges from mellow sweet to tangy or acidic sweet, with variable suggestions of pineapple, banana, pear, papaya, strawberry or other berry, and apple, depending on the variety. The ripened flesh is creamy white. When ripe, the skin is green and gives slightly to pressure. Some characterize the fruit flavor as a blend of banana, pineapple, papaya, peach, and strawberry. The fruit can be chilled and eaten with a spoon, which has earned it another nickname, the "ice cream fruit". In Chile and Peru, it is commonly used in ice creams and yogurt.
When the fruit is ripe and still has the fresh, fully mature green-yellow skin color, the texture is like that of a soft ripe pear or papaya. When the skin turns brown at room temperature, the fruit is no longer good for human consumption.
Brand
Chirimoya Cumbe is a well-known case involving collective marks in trademark law. The World Intellectual Property Organization has defined these collective marks as “signs which distinguish the geographical origin, material, mode of manufacturing or other common characteristics of goods or services of different enterprises using the collective mark.” The owner of a collective mark are members of an association of such enterprises. | Cherimoya | Wikipedia | 512 | 585460 | https://en.wikipedia.org/wiki/Cherimoya | Biology and health sciences | Other culinary fruits | Plants |
Cumbe is a valley in the Huarochiri province of Peru where the climatic conditions are favourable for growing chirimoya. The fruit produced in the Cumbe valley is considered of superior quality, with a large fruit size, soft skin, low seed index (number of seeds per 100 grams of fruit), and high nutrient value.
In 1997, Matildo Pérez, a peasant from a village community in the heights of Lima, decided to apply personally to the National Institute for the Defense of Competition and Intellectual Property of Peru (INDECOPI) for the registration of the trademark "Chirimoya Cumbe." The application was refused since no exclusive rights in generic names can be granted to a single person. Mr. Pérez appeared at INDECOPI again, this time with a delegation headed by the Deputy Mayor of Cumbe, to register the “Chirimoya Cumbe” as a trademark which would give the community in Lima exclusive rights with respect to the name “Cumbe”.
The INDECOPI officials explained that "Chirimoya Cumbe" is in fact an appellation of origin, not a trademark. To be more precise, the word “Cumbe” is an appellation of Peruvian origin, because the valley of Cumbe is a geographical area that gives certain distinctive properties to the Chirimoya grown there.
The people of Cumbe declined the proposition of appellation of origin: "It is said that with appellations of origin the State is the owner, and it is the State that authorizes use, and that is why we are saying no. We do not want the State to be the owner of the ‘Cumbe’ name."
After lengthy search for solutions, it was suggested that “Chirimoya Cumbe” should be registered as a “collective mark”, the owners of which would be the people of Cumbe and which would be used according to rules that they themselves would lay down.
In 2022, the name "Chirimoya Cumbe" has its own characteristic logo and is registered as a collective mark in the name of the village of Santo Toribio de Cumbe (in Class 31 of the International Classification).
Culture
The Moche culture of Peru had a fascination with agriculture and represented fruits and vegetables in their art; cherimoyas were often depicted in their ceramics.
Gallery | Cherimoya | Wikipedia | 477 | 585460 | https://en.wikipedia.org/wiki/Cherimoya | Biology and health sciences | Other culinary fruits | Plants |
Thyreophora ("shield bearers", often known simply as "armored dinosaurs") is a group of armored ornithischian dinosaurs that lived from the Early Jurassic until the end of the Cretaceous.
Thyreophorans are characterized by the presence of body armor lined up in longitudinal rows along the body. Primitive forms had simple, low, keeled scutes or osteoderms, whereas more derived forms developed more elaborate structures including spikes and plates. Most thyreophorans were herbivorous and had relatively small brains for their body size.
Thyreophora includes two major subgroups, Ankylosauria and Stegosauria. In both clades, the forelimbs were much shorter than the hindlimbs, particularly in stegosaurs. Thyreophora has been defined as the group consisting of all species more closely related to Ankylosaurus and Stegosaurus than to Iguanodon and Triceratops. It is the sister group of Cerapoda within Genasauria.
Characteristics
Members of Thyreophora are characterised by the presence of osteoderms (bony growths within the skin), with these osteoderms having lateral keels. Characters of the skull and jaws distinctive (synapomorphic) of thyreophorans include "absence of a deep elliptic fossa along the sutural line of the nasals, presence of a wide jugal, remodeling of skull dermal bone, down-turned dentary tooth row". Among primitive thyreophorans, Scutellosaurus was likely primarily bipedal, while the more quadrupedally adapted Scelidosaurus may have been bipedal for some of the time, particularly as a juvenile. Stegosaurs and ankylosaurs are thought to have been obligately quadrupedal.
Classification
Taxonomy
While ranked taxonomy has largely fallen out of favor among dinosaur paleontologists, a few 21st century publications have retained the use of ranks, though sources have differed on what its rank should be. Most have listed Thyreophora as an unranked taxon containing the traditional suborders Stegosauria and Ankylosauria, though Thyreophora is also sometimes classified as a suborder, with Ankylosauria and Stegosauria as infraorders. | Thyreophora | Wikipedia | 490 | 585468 | https://en.wikipedia.org/wiki/Thyreophora | Biology and health sciences | Ornitischians | Animals |
Phylogeny
Thyreophora was first named by Nopcsa in 1915. Thyreophora was defined as a clade by Paul Sereno in 1998, as "all genasaurs more closely related to Ankylosaurus than to Triceratops". Thyreophoroidea was first named by Nopcsa in 1928 and defined by Sereno in 1986, as "Scelidosaurus, Ankylosaurus, their most recent common ancestor and all of its descendants". Eurypoda was first named by Sereno in 1986 and defined by him in 1998, as "Stegosaurus, Ankylosaurus, their most recent common ancestor and all of their descendants".
In 2021, an international group of researchers led by Daniel Madzia registered almost all of the most commonly used ornithischian clades under the International Code of Phylogenetic Nomenclature, with the intent of standardizing their definitions. According to Madzia et al., Thyreophora is defined as the largest clade containing Ankylosaurus magniventris and Stegosaurus stenops but not Iguanodon bernissartensis and Triceratops horridus. They also defined the less inclusive Eurypoda as "the smallest clade containing Ankylosaurus magniventris and Stegosaurus stenops" to include the ankylosaurs and stegosaurs to the exclusion of basal thyreophorans. A later study conducted by André Fonseca and colleagues in 2024 gave a formal definition for Thyreophoroidea in the PhyloCode as "the smallest clade containing Ankylosaurus magniventris, Scelidosaurus harrisonii, and Stegosaurus stenops".
The following cladogram shows the results of the phylogenetic analysis Soto-Acuña et al. (2021). In their description of Jakapil the following year, Riguetti et al modified the same matrix and found it to occupy a position as the sister taxon to the Eurypoda. A similar result was found by Fonseca et al. in 2024. | Thyreophora | Wikipedia | 437 | 585468 | https://en.wikipedia.org/wiki/Thyreophora | Biology and health sciences | Ornitischians | Animals |
In 2020, as part of his monograph on Scelidosaurus, David Norman revised the relationships of early thyreophorans, finding that Stegosauria was the most basal branch, with Scutellosaurus, Emausaurus and Scelidosaurus being progressive stem groups to Ankylosauria, rather than to Stegosauria+Ankylosauria. A cladogram is given below: | Thyreophora | Wikipedia | 86 | 585468 | https://en.wikipedia.org/wiki/Thyreophora | Biology and health sciences | Ornitischians | Animals |
Teleostei (; Greek teleios "complete" + osteon "bone"), members of which are known as teleosts (), is, by far, the largest group of ray-finned fishes (class Actinopterygii), and contains 96% of all extant species of fish. The Teleostei, which is variously considered a division or an infraclass in different taxonomic systems, include over 26,000 species that are arranged in about 40 orders and 448 families. Teleosts range from giant oarfish measuring or more, and ocean sunfish weighing over , to the minute male anglerfish Photocorynus spiniceps, just long. Including not only torpedo-shaped fish built for speed, teleosts can be flattened vertically or horizontally, be elongated cylinders or take specialised shapes as in anglerfish and seahorses.
The difference between teleosts and other bony fish lies mainly in their jaw bones; teleosts have a movable premaxilla and corresponding modifications in the jaw musculature which make it possible for them to protrude their jaws outwards from the mouth. This is of great advantage, enabling them to grab prey and draw it into the mouth. In more derived teleosts, the enlarged premaxilla is the main tooth-bearing bone, and the maxilla, which is attached to the lower jaw, acts as a lever, pushing and pulling the premaxilla as the mouth is opened and closed. Other bones further back in the mouth serve to grind and swallow food. Another difference is that the upper and lower lobes of the tail (caudal) fin are about equal in size. The spine ends at the caudal peduncle, distinguishing this group from other fish in which the spine extends into the upper lobe of the tail fin.
Teleosts have adopted a range of reproductive strategies. Most use external fertilisation: the female lays a batch of eggs, the male fertilises them and the larvae develop without any further parental involvement. A fair proportion of teleosts are sequential hermaphrodites, starting life as females and transitioning to males at some stage, with a few species reversing this process. A small percentage of teleosts are viviparous and some provide parental care with typically the male fish guarding a nest and fanning the eggs to keep them well-oxygenated. | Teleost | Wikipedia | 501 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
Teleosts are economically important to humans, as is shown by their depiction in art over the centuries. The fishing industry harvests them for food, and anglers attempt to capture them for sport. Some species are farmed commercially, and this method of production is likely to be increasingly important in the future. Others are kept in aquariums or used in research, especially in the fields of genetics and developmental biology.
Anatomy
Distinguishing features of the teleosts are mobile premaxilla, elongated neural arches at the end of the caudal fin and unpaired basibranchial toothplates. The premaxilla is unattached to the neurocranium (braincase); it plays a role in protruding the mouth and creating a circular opening. This lowers the pressure inside the mouth, sucking the prey inside. The lower jaw and maxilla are then pulled back to close the mouth, and the fish is able to grasp the prey. By contrast, mere closure of the jaws would risk pushing food out of the mouth. In more advanced teleosts, the premaxilla is enlarged and has teeth, while the maxilla is toothless. The maxilla functions to push both the premaxilla and the lower jaw forward. To open the mouth, an adductor muscle pulls back the top of the maxilla, pushing the lower jaw forward. In addition, the maxilla rotates slightly, which pushes forward a bony process that interlocks with the premaxilla. | Teleost | Wikipedia | 304 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
The pharyngeal jaws of teleosts, a second set of jaws contained within the throat, are composed of five branchial arches, loops of bone which support the gills. The first three arches include a single basibranchial surrounded by two hypobranchials, ceratobranchials, epibranchials and pharyngobranchials. The median basibranchial is covered by a toothplate. The fourth arch is composed of pairs of ceratobranchials and epibranchials, and sometimes additionally, some pharyngobranchials and a basibranchial. The base of the lower pharyngeal jaws is formed by the fifth ceratobranchials while the second, third and fourth pharyngobranchials create the base of the upper. In the more basal teleosts the pharyngeal jaws consist of well-separated thin parts that attach to the neurocranium, pectoral girdle, and hyoid bar. Their function is limited to merely transporting food, and they rely mostly on lower pharyngeal jaw activity. In more derived teleosts the jaws are more powerful, with left and right ceratobranchials fusing to become one lower jaw; the pharyngobranchials fuse to create a large upper jaw that articulates with the neurocranium. They have also developed a muscle that allows the pharyngeal jaws to have a role in grinding food in addition to transporting it.
The caudal fin is homocercal, meaning the upper and lower lobes are about equal in size. The spine ends at the caudal peduncle, the base of the caudal fin, distinguishing this group from those in which the spine extends into the upper lobe of the caudal fin, such as most fish from the Paleozoic (541 to 252 million years ago). The neural arches are elongated to form uroneurals which provide support for this upper lobe. | Teleost | Wikipedia | 424 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
Teleosts tend to be quicker and more flexible than more basal bony fishes. Their skeletal structure has evolved towards greater lightness. While teleost bones are well calcified, they are constructed from a scaffolding of struts, rather than the dense cancellous bones of holostean fish. In addition, the lower jaw of the teleost is reduced to just three bones; the dentary, the angular bone and the articular bone. The genital and urinary tracts end behind the anus in the genital papilla; this is observed to sex teleosts.
Evolution and phylogeny
External relationships
The teleosts were first recognised as a distinct group by the German ichthyologist Johannes Peter Müller in 1845. The name is from Greek teleios, "complete" + osteon, "bone". Müller based this classification on certain soft tissue characteristics, which would prove to be problematic, as it did not take into account the distinguishing features of fossil teleosts. In 1966, Greenwood et al. provided a more solid classification. The oldest fossils of teleosteomorphs (the stem group from which teleosts later evolved) date back to the Triassic period (Prohalecites, Pholidophorus). However, it has been suggested that teleosts probably first evolved already during the Paleozoic era. During the Mesozoic and Cenozoic eras they diversified widely, and as a result, 96% of all living fish species are teleosts.
The cladogram below shows the evolutionary relationships of the teleosts to other extant clades of bony fish, and to the four-limbed vertebrates (tetrapods) that evolved from a related group of bony fish during the Devonian period. Approximate divergence dates (in millions of years, mya) are from Near et al., 2012.
Internal relationships | Teleost | Wikipedia | 395 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
The phylogeny of the teleosts has been subject to long debate, without consensus on either their phylogeny or the timing of the emergence of the major groups before the application of modern DNA-based cladistic analysis. Near et al. (2012) explored the phylogeny and divergence times of every major lineage, analysing the DNA sequences of 9 unlinked genes in 232 species. They obtained well-resolved phylogenies with strong support for the nodes (so, the pattern of branching shown is likely to be correct). They calibrated (set actual values for) branching times in this tree from 36 reliable measurements of absolute time from the fossil record. The teleosts are divided into the major clades shown on the cladogram, with dates, following Near et al. More recent research divide the teleosts into two major groups: Eloposteoglossocephala (Elopomorpha + Osteoglossomorpha) and Clupeocephala (the rest of the teleosts).
The most diverse group of teleost fish today are the Percomorpha, which include, among others, the tuna, seahorses, gobies, cichlids, flatfish, wrasse, perches, anglerfish, and pufferfish. Teleosts, and percomorphs in particular, thrived during the Cenozoic era. Fossil evidence shows that there was a major increase in size and abundance of teleosts immediately after the mass extinction event at the Cretaceous-Paleogene boundary ca. 66 mya.
Evolutionary trends
The first fossils assignable to this diverse group appear in the Early Triassic, after which teleosts accumulated novel body shapes predominantly gradually for the first 150 million years of their evolution (Early Triassic through early Cretaceous). | Teleost | Wikipedia | 383 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
The most basal of the living teleosts are the Elopomorpha (eels and allies) and the Osteoglossomorpha (elephantfishes and allies). There are 800 species of elopomorphs. They have thin leaf-shaped larvae known as leptocephali, specialised for a marine environment. Among the elopomorphs, eels have elongated bodies with lost pelvic girdles and ribs and fused elements in the upper jaw. The 200 species of osteoglossomorphs are defined by a bony element in the tongue. This element has a basibranchial behind it, and both structures have large teeth which are paired with the teeth on the parasphenoid in the roof of the mouth. The clade Otocephala includes the Clupeiformes (herrings) and Ostariophysi (carps, catfishes and allies). Clupeiformes consists of 350 living species of herring and herring-like fishes. This group is characterised by an unusual abdominal scute and a different arrangement of the hypurals. In most species, the swim bladder extends to the braincase and plays a role in hearing. Ostariophysi, which includes most freshwater fishes, includes species that have developed some unique adaptations. One is the Weberian apparatus, an arrangement of bones (Weberian ossicles) connecting the swim bladder to the inner ear. This enhances their hearing, as sound waves make the bladder vibrate, and the bones transport the vibrations to the inner ear. They also have a chemical alarm system; when a fish is injured, the warning substance gets in the water, alarming nearby fish. | Teleost | Wikipedia | 351 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
The majority of teleost species belong to the clade Euteleostei, which consists of 17,419 species classified in 2,935 genera and 346 families. Shared traits of the euteleosts include similarities in the embryonic development of the bony or cartilaginous structures located between the head and dorsal fin (supraneural bones), an outgrowth on the stegural bone (a bone located near the neural arches of the tail), and caudal median cartilages located between hypurals of the caudal base. The majority of euteleosts are in the clade Neoteleostei. A derived trait of neoteleosts is a muscle that controls the pharyngeal jaws, giving them a role in grinding food. Within neoteleosts, members of the Acanthopterygii have a spiny dorsal fin which is in front of the soft-rayed dorsal fin. This fin helps provide thrust in locomotion and may also play a role in defense. Acanthomorphs have developed spiny ctenoid scales (as opposed to the cycloid scales of other groups), tooth-bearing premaxilla and greater adaptations to high speed swimming.
The adipose fin, which is present in over 6,000 teleost species, is often thought to have evolved once in the lineage and to have been lost multiple times due to its limited function. A 2014 study challenges this idea and suggests that the adipose fin is an example of convergent evolution. In Characiformes, the adipose fin develops from an outgrowth after the reduction of the larval fin fold, while in Salmoniformes, the fin appears to be a remnant of the fold.
Diversity | Teleost | Wikipedia | 362 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
There are over 26,000 species of teleosts, in about 40 orders and 448 families, making up 96% of all extant species of fish. Approximately 12,000 of the total 26,000 species are found in freshwater habitats. Teleosts are found in almost every aquatic environment and have developed specializations to feed in a variety of ways as carnivores, herbivores, filter feeders and parasites. The longest teleost is the giant oarfish, reported at and more, but this is dwarfed by the extinct Leedsichthys, one individual of which has been estimated to have a length of . The heaviest teleost is believed to be the ocean sunfish, with a specimen landed in 2003 having an estimated weight of , while the smallest fully mature adult is the male anglerfish Photocorynus spiniceps which can measure just , though the female at is much larger. The stout infantfish is the smallest and lightest adult fish and is in fact the smallest vertebrate in the world; the females measures and the male just .
Open water fish are usually streamlined like torpedoes to minimize turbulence as they move through the water. Reef fish live in a complex, relatively confined underwater landscape and for them, manoeuvrability is more important than speed, and many of them have developed bodies which optimize their ability to dart and change direction. Many have laterally compressed bodies (flattened from side to side) allowing them to fit into fissures and swim through narrow gaps; some use their pectoral fins for locomotion and others undulate their dorsal and anal fins. Some fish have grown dermal (skin) appendages for camouflage; the prickly leather-jacket is almost invisible among the seaweed it resembles and the tasselled scorpionfish invisibly lurks on the seabed ready to ambush prey. Some like the foureye butterflyfish have eyespots to startle or deceive, while others such as lionfish have aposematic coloration to warn that they are toxic or have venomous spines. | Teleost | Wikipedia | 425 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
Flatfish are demersal fish (bottom-feeding fish) that show a greater degree of asymmetry than any other vertebrates. The larvae are at first bilaterally symmetrical but they undergo metamorphosis during the course of their development, with one eye migrating to the other side of the head, and they simultaneously start swimming on their side. This has the advantage that, when they lie on the seabed, both eyes are on top, giving them a broad field of view. The upper side is usually speckled and mottled for camouflage, while the underside is pale.
Some teleosts are parasites. Remoras have their front dorsal fins modified into large suckers with which they cling onto a host animal such as a whale, sea turtle, shark or ray, but this is probably a commensal rather than parasitic arrangement because both remora and host benefit from the removal of ectoparasites and loose flakes of skin. More harmful are the catfish that enter the gill chambers of fish and feed on their blood and tissues. The snubnosed eel, though usually a scavenger, sometimes bores into the flesh of a fish, and has been found inside the heart of a shortfin mako shark.
Some species, such as electric eels, can produce powerful electric currents, strong enough to stun prey. Other fish, such as knifefish, generate and sense weak electric fields to detect their prey; they swim with straight backs to avoid distorting their electric fields. These currents are produced by modified muscle or nerve cells.
Distribution
Teleosts are found worldwide and in most aquatic environments, including warm and cold seas, flowing and still freshwater, and even, in the case of the desert pupfish, isolated and sometimes hot and saline bodies of water in deserts. Teleost diversity becomes low at extremely high latitudes; at Franz Josef Land, up to 82°N, ice cover and water temperatures below for a large part of the year limit the number of species; 75 percent of the species found there are endemic to the Arctic. | Teleost | Wikipedia | 423 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
Of the major groups of teleosts, the Elopomorpha, Clupeomorpha and Percomorpha (perches, tunas and many others) all have a worldwide distribution and are mainly marine; the Ostariophysi and Osteoglossomorpha are worldwide but mainly freshwater, the latter mainly in the tropics; the Atherinomorpha (guppies, etc.) have a worldwide distribution, both fresh and salt, but are surface-dwellers. In contrast, the Esociformes (pikes) are limited to freshwater in the Northern Hemisphere, while the Salmoniformes (salmon, trout) are found in both Northern and Southern temperate zones in freshwater, some species migrating to and from the sea. The Paracanthopterygii (cods, etc.) are Northern Hemisphere fish, with both salt and freshwater species.
Some teleosts are migratory; certain freshwater species move within river systems on an annual basis; other species are anadromous, spending their lives at sea and moving inland to spawn, salmon and striped bass being examples. Others, exemplified by the eel, are catadromous, doing the reverse. The fresh water European eel migrates across the Atlantic Ocean as an adult to breed in floating seaweed in the Sargasso Sea. The adults spawn here and then die, but the developing young are swept by the Gulf Stream towards Europe. By the time they arrive, they are small fish and enter estuaries and ascend rivers, overcoming obstacles in their path to reach the streams and ponds where they spend their adult lives.
Teleosts including the brown trout and the scaly osman are found in mountain lakes in Kashmir at altitudes as high as . Teleosts are found at extreme depths in the oceans; the hadal snailfish has been seen at a depth of , and a related (unnamed) species has been seen at .
Physiology
Respiration | Teleost | Wikipedia | 397 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
The major means of respiration in teleosts, as in most other fish, is the transfer of gases over the surface of the gills as water is drawn in through the mouth and pumped out through the gills. Apart from the swim bladder, which contains a small amount of air, the body does not have oxygen reserves, and respiration needs to be continuous over the fish's life. Some teleosts exploit habitats where the oxygen availability is low, such as stagnant water or wet mud; they have developed accessory tissues and organs to support gas exchange in these habitats.
Several genera of teleosts have independently developed air-breathing capabilities, and some have become amphibious. Some combtooth blennies emerge to feed on land, and freshwater eels are able to absorb oxygen through damp skin. Mudskippers can remain out of water for considerable periods, exchanging gases through skin and mucous membranes in the mouth and pharynx. Swamp eels have similar well-vascularised mouth-linings, and can remain out of water for days and go into a resting state (aestivation) in mud. The anabantoids have developed an accessory breathing structure known as the labyrinth organ on the first gill arch and this is used for respiration in air, and airbreathing catfish have a similar suprabranchial organ. Certain other catfish, such as the Loricariidae, are able to respire through air held in their digestive tracts.
Sensory systems
Teleosts possess highly developed sensory organs. Nearly all daylight fish have colour vision at least as good as a normal human's. Many fish also have chemoreceptors responsible for acute senses of taste and smell. Most fish have sensitive receptors that form the lateral line system, which detects gentle currents and vibrations, and senses the motion of nearby fish and prey. Fish sense sounds in a variety of ways, using the lateral line, the swim bladder, and in some species the Weberian apparatus. Fish orient themselves using landmarks, and may use mental maps based on multiple landmarks or symbols. Experiments with mazes show that fish possess the spatial memory needed to make such a mental map.
Osmoregulation | Teleost | Wikipedia | 441 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
The skin of a teleost is largely impermeable to water, and the main interface between the fish's body and its surroundings is the gills. In freshwater, teleost fish gain water across their gills by osmosis, while in seawater they lose it. Similarly, salts diffuse outwards across the gills in freshwater and inwards in salt water. The European flounder spends most of its life in the sea but often migrates into estuaries and rivers. In the sea in one hour, it can gain Na+ ions equivalent to forty percent of its total free sodium content, with 75 percent of this entering through the gills and the remainder through drinking. By contrast, in rivers there is an exchange of just two percent of the body Na+ content per hour. As well as being able to selectively limit salt and water exchanged by diffusion, there is an active mechanism across the gills for the elimination of salt in sea water and its uptake in fresh water.
Thermoregulation
Fish are cold-blooded, and in general their body temperature is the same as that of their surroundings. They gain and lose heat through their skin, and regulate their circulation in response to changes in water temperature by increasing or reducing the blood flow to the gills. Metabolic heat generated in the muscles or gut is quickly dissipated through the gills, with blood being diverted away from the gills during exposure to cold. Because of their relative inability to control their blood temperature, most teleosts can only survive in a small range of water temperatures.
Teleost species that inhabit colder waters have a higher proportion of unsaturated fatty acids in brain cell membranes compared to fish from warmer waters, which allows them to maintain appropriate membrane fluidity in the environments in which they live. When cold acclimated, teleost fish show physiological changes in skeletal muscle that include increased mitochondrial and capillary density. This reduces diffusion distances and aids in the production of aerobic ATP, which helps to compensate for the drop in metabolic rate associated with colder temperatures. | Teleost | Wikipedia | 413 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
Tuna and other fast-swimming ocean-going fish maintain their muscles at higher temperatures than their environment for efficient locomotion. Tuna achieve muscle temperatures or even higher above the surroundings by having a counterflow system in which the metabolic heat produced by the muscles and present in the venous blood, pre-warms the arterial blood before it reaches the muscles. Other adaptations of tuna for speed include a streamlined, spindle-shaped body, fins designed to reduce drag, and muscles with a raised myoglobin content, which gives these a reddish colour and makes for a more efficient use of oxygen. In polar regions and in the deep ocean, where the temperature is a few degrees above freezing point, some large fish, such as the swordfish, marlin and tuna, have a heating mechanism which raises the temperature of the brain and eye, allowing them significantly better vision than their cold-blooded prey.
Buoyancy
The body of a teleost is denser than water, so fish must compensate for the difference, or they will sink. A defining feature of Actinopteri (Chondrostei, Holostei and teleosts) is the swim bladder. Originally present in the last common ancestor of the teleosts, it has since been lost independently at least 30–32 times in at least 79 of 425 families of teleosts where the swim bladder is absent in one or more species. This absence is often the case in fast-swimming fishes such as the tuna and mackerel. The swim bladder helps fish adjusting their buoyancy through manipulation of gases, which allows them to stay at the current water depth, or ascend or descend without having to waste energy in swimming. In the more primitive groups like some minnows, the swim bladder is open (physostomous) to the esophagus. In fish where the swim bladder is closed (physoclistous), the gas content is controlled through the rete mirabilis, a network of blood vessels serving as a countercurrent gas exchanger between the swim bladder and the blood.
Locomotion | Teleost | Wikipedia | 430 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
A typical teleost fish has a streamlined body for rapid swimming, and locomotion is generally provided by a lateral undulation of the hindmost part of the trunk and the tail, propelling the fish through the water. There are many exceptions to this method of locomotion, especially where speed is not the main objective; among rocks and on coral reefs, slow swimming with great manoeuvrability may be a desirable attribute. Eels locomote by wiggling their entire bodies. Living among seagrasses and algae, the seahorse adopts an upright posture and moves by fluttering its pectoral fins, and the closely related pipefish moves by rippling its elongated dorsal fin. Gobies "hop" along the substrate, propping themselves up and propelling themselves with their pectoral fins. Mudskippers move in much the same way on terrestrial ground. In some species, a pelvic sucker allows them to climb, and the Hawaiian freshwater goby climbs waterfalls while migrating. Gurnards have three pairs of free rays on their pectoral fins which have a sensory function but on which they can walk along the substrate. Flying fish launch themselves into the air and can glide on their enlarged pectoral fins for hundreds of metres.
Sound production
The ability to produce sound for communication appears to have evolved independently in several teleost lineages. Sounds are produced either by stridulation or by vibrating the swim bladder. In the Sciaenidae, the muscles that attach to the swim bladder cause it to oscillate rapidly, creating drumming sounds. Marine catfishes, sea horses and grunts stridulate by rubbing together skeletal parts, teeth or spines. In these fish, the swim bladder may act as a resonator. Stridulation sounds are predominantly from 1000–4000 Hz, though sounds modified by the swim bladder have frequencies lower than 1000 Hz.
Reproduction and lifecycle | Teleost | Wikipedia | 387 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
Most teleost species are oviparous, having external fertilisation with both eggs and sperm being released into the water for fertilisation. Internal fertilisation occurs in 500 to 600 species of teleosts but is more typical for Chondrichthyes and many tetrapods. This involves the male inseminating the female with an intromittent organ. Fewer than one in a million of externally fertilised eggs survives to develop into a mature fish, but there is a much better chance of survival among the offspring of members of about a dozen families which are viviparous. In these, the eggs are fertilised internally and retained in the female during development. Some of these species, like the live-bearing aquarium fish in the family Poeciliidae, are ovoviviparous; each egg has a yolk sac which nourishes the developing embryo, and when this is exhausted, the egg hatches and the larva is expelled into the water column. Other species, like the splitfins in the family Goodeidae, are fully viviparous, with the developing embryo nurtured from the maternal blood supply via a placenta-like structure that develops in the uterus. Oophagy is practised by a few species, such as Nomorhamphus ebrardtii; the mother lays unfertilised eggs on which the developing larvae feed in the uterus, and intrauterine cannibalism has been reported in some halfbeaks.
There are two major reproductive strategies of teleosts; semelparity and iteroparity. In the former, an individual breeds once after reaching maturity and then dies. This is because the physiological changes that come with reproduction eventually lead to death. Salmon of the genus Oncorhynchus are well known for this feature; they hatch in fresh water and then migrate to the sea for up to four years before travelling back to their place of birth where they spawn and die. Semelparity is also known to occur in some eels and smelts. The majority of teleost species have iteroparity, where mature individuals can breed multiple times during their lives.
Sex identity and determination | Teleost | Wikipedia | 464 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
88 percent of teleost species are gonochoristic, having individuals that remain either male or female throughout their adult lives. The sex of an individual can be determined genetically as in birds and mammals, or environmentally as in reptiles. In some teleosts, both genetics and the environment play a role in determining sex. For species whose sex is determined by genetics, it can come in three forms. In monofactorial sex determination, a single-locus determines sex inheritance. Both the XY sex-determination system and ZW sex-determination system exist in teleost species. Some species, such as the southern platyfish, have both systems and a male can be determined by XY or ZZ depending on the population.
Multifactorial sex determination occurs in numerous Neotropical species and involves both XY and ZW systems. Multifactorial systems involve rearrangements of sex chromosomes and autosomes. For example, the darter characine has a ZW multifactorial system where the female is determined by ZW1W2 and the male by ZZ. The wolf fish has a XY multifactorial system where females are determined by X1X1X2X2 and the male by X1X2Y. Some teleosts, such as zebrafish, have a polyfactorial system, where there are several genes which play a role in determining sex. Environment-dependent sex determination has been documented in at least 70 species of teleost. Temperature is the main factor, but pH levels, growth rate, density and social environment may also play a role. For the Atlantic silverside, spawning in colder waters creates more females, while warmer waters create more males.
Hermaphroditism | Teleost | Wikipedia | 362 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
Some teleost species are hermaphroditic, which can come in two forms: simultaneous and sequential. In the former, both spermatozoa and eggs are present in the gonads. Simultaneous hermaphroditism typically occurs in species that live in the ocean depths, where potential mates are sparsely dispersed. Self-fertilisation is rare and has only been recorded in two species, Kryptolebias marmoratus and Kryptolebias hermaphroditus. With sequential hermaphroditism, individuals may function as one sex early in their adult life and switch later in life. Species with this condition include parrotfish, wrasses, sea basses, flatheads, sea breams and lightfishes.
Protandry is when an individual starts out male and becomes female while the reverse condition is known as protogyny, the latter being more common. Changing sex can occur in various contexts. In the bluestreak cleaner wrasse, where males have harems of up to ten females, if the male is removed the largest and most dominant female develops male-like behaviour and eventually testes. If she is removed, the next ranking female takes her place. In the species Anthias squamipinnis, where individuals gather into large groups and females greatly outnumber males, if a certain number of males are removed from a group, the same number of females change sex and replace them. In clownfish, individuals live in groups and only the two largest in a group breed: the largest female and the largest male. If the female dies, the male switches sexes and the next largest male takes his place.
In deep-sea anglerfish (sub-order Ceratioidei), the much smaller male becomes permanently attached to the female and degenerates into a sperm-producing attachment. The female and their attached male become a "semi-hermaphroditic unit".
Mating tactics | Teleost | Wikipedia | 407 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
There are several different mating systems among teleosts. Some species are promiscuous, where both males and females breed with multiple partners and there are no obvious mate choices. This has been recorded in Baltic herring, Guppies, Nassau groupers, humbug damselfish, cichlids and creole wrasses. Polygamy, where one sex has multiple partners can come in many forms. Polyandry consists of one adult female breeding with multiple males, which only breed with that female. This is rare among teleosts, and fish in general, but is found in the clownfish. In addition, it may also exist to an extent among anglerfish, where some females have more than one male attached to them. Polygyny, where one male breeds with multiple females, is much more common. This is recorded in Sculpins, sunfish, darters, damselfish and cichlids where multiple females may visit a territorial male that guards and takes care of eggs and young. Polygyny may also involve a male guarding a harem of several females. This occurs in coral reef species, such as damselfishes, wrasses, parrotfishes, surgeonfishes, triggerfishes and tilefishes.
Lek breeding, where males congregate to display to females, has been recorded in at least one species Cyrtocara eucinostomus. Lek-like breeding systems have also been recorded in several other species. In monogamous species, males and females may form pair bonds and breed exclusively with their partners. This occurs in North American freshwater catfishes, many butterflyfishes, sea horses and several other species. Courtship in teleosts plays a role in species recognition, strengthening pair bonds, spawning site position and gamete release synchronisation. This includes colour changes, sound production and visual displays (fin erection, rapid swimming, breaching), which is often done by the male. Courtship may be done by a female to overcome a territorial male that would otherwise drive her away. | Teleost | Wikipedia | 423 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
Sexual dimorphism exists in some species. Individuals of one sex, usually males develop secondary sexual characteristics that increase their chances of reproductive success. In dolphinfish, males have larger and blunter heads than females. In several minnow species, males develop swollen heads and small bumps known as breeding tubercles during the breeding season. The male green humphead parrotfish has a more well-developed forehead with an "ossified ridge" which plays a role in ritualised headbutting. Dimorphism can also take the form of differences in coloration. Again, it is usually the males that are brightly coloured; in killifishes, rainbowfishes and wrasses the colours are permanent while in species like minnows, sticklebacks, darters and sunfishes, the colour changes with seasons. Such coloration can be very conspicuous to predators, showing that the drive to reproduce can be stronger than that to avoid predation.
Males that have been unable to court a female successfully may try to achieve reproductive success in other ways. In sunfish species, like the bluegill, larger, older males known as parental males, which have successfully courted a female, construct nests for the eggs they fertilise. Smaller satellite males mimic female behaviour and coloration to access a nest and fertilise the eggs. Other males, known as sneaker males, lurk nearby and then quickly dash to the nest, fertilising on the run. These males are smaller than satellite males. Sneaker males also exist in Oncorhynchus salmon, where small males that were unable to establish a position near a female dash in while the large dominant male is spawning with the female.
Spawning sites and parental care
Teleosts may spawn in the water column or, more commonly, on the substrate. Water column spawners are mostly limited to coral reefs; the fish will rush towards the surface and release their gametes. This appears to protect the eggs from some predators and allow them to disperse widely via currents. They receive no parental care. Water column spawners are more likely than substrate spawners to spawn in groups. Substrate spawning commonly occurs in nests, rock crevices or even burrows. Some eggs can stick to various surfaces like rocks, plants, wood or shells. | Teleost | Wikipedia | 465 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
Of the oviparous teleosts, most (79 percent) do not provide parental care. Male care is far more common than female care. Male territoriality "preadapts" a species to evolve male parental care. One unusual example of female parental care is in discuses, which provide nutrients for their developing young in the form of mucus. Some teleost species have their eggs or young attached to or carried in their bodies. For sea catfishes, cardinalfishes, jawfishes and some others, the egg may be incubated or carried in the mouth, a practice known as mouthbrooding. In some African cichlids, the eggs may be fertilised there. In species like the banded acara, young are brooded after they hatch and this may be done by both parents. The timing of the release of young varies between species; some mouthbrooders release new-hatched young while other may keep then until they are juveniles. In addition to mouthbrooding, some teleost have also developed structures to carry young. Male nurseryfish have a bony hook on their foreheads to carry fertilised eggs; they remain on the hook until they hatch. For seahorses, the male has a brooding pouch where the female deposits the fertilised eggs and they remain there until they become free-swimming juveniles. Female banjo catfishes have structures on their belly to which the eggs attach.
In some parenting species, young from a previous spawning batch may stay with their parents and help care for the new young. This is known to occur in around 19 species of cichlids in Lake Tanganyika. These helpers take part in cleaning and fanning eggs and larvae, cleaning the breeding hole and protecting the territory. They have reduced growth rate but gain protection from predators. Brood parasitism also exists among teleosts; minnows may spawn in sunfish nests as well as nests of other minnow species. The cuckoo catfish is known for laying eggs on the substrate as mouthbrooding cichclids collect theirs and the young catfish will eat the cichlid larvae. Filial cannibalism occurs in some teleost families and may have evolved to combat starvation.
Growth and development | Teleost | Wikipedia | 466 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
Teleosts have four major life stages: the egg, the larva, the juvenile and the adult. Species may begin life in a pelagic environment or a demersal environment (near the seabed). Most marine teleosts have pelagic eggs, which are light, transparent and buoyant with thin envelopes. Pelagic eggs rely on the ocean currents to disperse and receive no parental care. When they hatch, the larvae are planktonic and unable to swim. They have a yolk sac attached to them which provides nutrients. Most freshwater species produce demersal eggs which are thick, pigmented, relatively heavy and able to stick to substrates. Parental care is much more common among freshwater fish. Unlike their pelagic counterparts, demersal larvae are able to swim and feed as soon as they hatch. Larval teleosts often look very different from adults, particularly in marine species. Some larvae were even considered different species from the adults. Larvae have high mortality rates, most die from starvation or predation within their first week. As they grow, survival rates increase and there is greater physiological tolerance and sensitivity, ecological and behavioural competence.
At the juvenile stage, a teleost looks more like its adult form. At this stage, its axial skeleton, internal organs, scales, pigmentation and fins are fully developed. The transition from larvae to juvenile can be short and fairly simple, lasting minutes or hours as in some damselfish, while in other species, like salmon, squirrelfish, gobies and flatfishes, the transition is more complex and takes several weeks to complete. At the adult stage, a teleost is able to produce viable gametes for reproduction. Like many fish, teleosts continue to grow throughout their lives. Longevity depends on the species with some gamefish like European perch and largemouth bass living up to 25 years. Rockfish appear to be the longest living teleosts with some species living over 100 years.
Shoaling and schooling | Teleost | Wikipedia | 408 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
Many teleosts form shoals, which serve multiple purposes in different species. Schooling is sometimes an antipredator adaptation, offering improved vigilance against predators. It is often more efficient to gather food by working as a group, and individual fish optimise their strategies by choosing to join or leave a shoal. When a predator has been noticed, prey fish respond defensively, resulting in collective shoal behaviours such as synchronised movements. Responses do not consist only of attempting to hide or flee; antipredator tactics include for example scattering and reassembling. Fish also aggregate in shoals to spawn.
Relationship with humans
Economic importance
Teleosts are economically important in different ways. They are captured for food around the world. A small number of species such as herring, cod, pollock, anchovy, tuna and mackerel provide people with millions of tons of food per year, while many other species are fished in smaller amounts. They provide a large proportion of the fish caught for sport. Commercial and recreational fishing together provide millions of people with employment.
A small number of productive species including carp, salmon, tilapia and catfish are farmed commercially, producing millions of tons of protein-rich food per year. The UN's Food and Agriculture Organization expects production to increase sharply so that by 2030, perhaps sixty-two percent of food fish will be farmed.
Fish are consumed fresh, or may be preserved by traditional methods, which include combinations of drying, smoking, and salting, or fermentation. Modern methods of preservation include freezing, freeze-drying, and heat processing (as in canning). Frozen fish products include breaded or battered fillets, fish fingers and fishcakes. Fish meal is used as a food supplement for farmed fish and for livestock. Fish oils are made either from fish liver, especially rich in vitamins A and D, or from the bodies of oily fish such as sardine and herring, and used as food supplements and to treat vitamin deficiencies.
Some smaller and more colourful species serve as aquarium specimens and pets. Sea wolves are used in the leather industry. Isinglass is made from thread fish and drum fish.
Impact on stocks | Teleost | Wikipedia | 451 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
Human activities have affected stocks of many species of teleost, through overfishing, pollution and global warming. Among many recorded instances, overfishing caused the complete collapse of the Atlantic cod population off Newfoundland in 1992, leading to Canada's indefinite closure of the fishery. Pollution, especially in rivers and along coasts, has harmed teleosts as sewage, pesticides and herbicides have entered the water. Many pollutants, such as heavy metals, organochlorines, and carbamates interfere with teleost reproduction, often by disrupting their endocrine systems. In the roach, river pollution has caused the intersex condition, in which an individual's gonads contain both cells that can make male gametes (such as spermatogonia) and cells that can make female gametes (such as oogonia). Since endocrine disruption also affects humans, teleosts are used to indicate the presence of such chemicals in water. Water pollution caused local extinction of teleost populations in many northern European lakes in the second half of the twentieth century.
The effects of climate change on teleosts could be powerful but are complex. For example, increased winter precipitation (rain and snow) could harm populations of freshwater fish in Norway, whereas warmer summers could increase growth of adult fish. In the oceans, teleosts may be able to cope with warming, as it is simply an extension of natural variation in climate. It is uncertain how ocean acidification, caused by rising carbon dioxide levels, might affect teleosts.
Other interactions
A few teleosts are dangerous. Some, like eeltail catfish (Plotosidae), scorpionfish (Scorpaenidae) or stonefish (Synanceiidae) have venomous spines that can seriously injure or kill humans. Some, like the electric eel and the electric catfish, can give a severe electric shock. Others, such as the piranha and barracuda, have a powerful bite and have sometimes attacked human bathers. Reports indicate that some of the catfish family can be large enough to prey on human bathers.
Medaka and zebrafish are used as research models for studies in genetics and developmental biology. The zebrafish is the most commonly used laboratory vertebrate, offering the advantages of genetic similarity to mammals, small size, simple environmental needs, transparent larvae permitting non-invasive imaging, plentiful offspring, rapid growth, and the ability to absorb mutagens added to their water.
In art | Teleost | Wikipedia | 509 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
Teleost fishes have been frequent subjects in art, reflecting their economic importance, for at least 14,000 years. They were commonly worked into patterns in Ancient Egypt, acquiring mythological significance in Ancient Greece and Rome, and from there into Christianity as a religious symbol; artists in China and Japan similarly use fish images symbolically. Teleosts became common in Renaissance art, with still life paintings reaching a peak of popularity in the Netherlands in the 17th century. In the 20th century, different artists such as Klee, Magritte, Matisse and Picasso used representations of teleosts to express radically different themes, from attractive to violent. The zoologist and artist Ernst Haeckel painted teleosts and other animals in his 1904 Kunstformen der Natur. Haeckel had become convinced by Goethe and Alexander von Humboldt that by making accurate depictions of unfamiliar natural forms, such as from the deep oceans, he could not only discover "the laws of their origin and evolution but also to press into the secret parts of their beauty by sketching and painting". | Teleost | Wikipedia | 214 | 326787 | https://en.wikipedia.org/wiki/Teleost | Biology and health sciences | Actinopterygii | Animals |
The toothed whales (also called odontocetes, systematic name Odontoceti) are a clade of cetaceans that includes dolphins, porpoises, and all other whales with teeth, such as beaked whales and the sperm whales. 73 species of toothed whales are described. They are one of two living groups of cetaceans, the other being the baleen whales (Mysticeti), which have baleen instead of teeth. The two groups are thought to have diverged around 34 million years ago (mya).
Toothed whales range in size from the and vaquita to the and sperm whale. Several species of odontocetes exhibit sexual dimorphism, in that there are size or other morphological differences between females and males. They have streamlined bodies and two limbs that are modified into flippers. Some can travel at up to 30 knots. Odontocetes have conical teeth designed for catching fish or squid. They have well-developed hearing that is well adapted for both air and water, so much so that some can survive even if they are blind. Some species are well adapted for diving to great depths. Almost all have a layer of fat, or blubber, under the skin to keep warm in the cold water, with the exception of river dolphins.
Toothed whales consist of some of the most widespread mammals, but some, as with the vaquita, are restricted to certain areas. Odontocetes feed largely on fish and squid, but a few, like the orca, feed on mammals, such as pinnipeds. Males typically mate with multiple females every year, making them polygynous. Females mate every two to three years. Calves are typically born in the spring and summer, and females bear the responsibility for raising them, but more sociable species rely on the family group to care for calves. Many species, mainly dolphins, are highly sociable, with some pods reaching over a thousand individuals. | Toothed whale | Wikipedia | 407 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
Once hunted for their products, cetaceans are now protected by international law. Some species are very intelligent. At the 2012 meeting of the American Association for the Advancement of Science, support was reiterated for a cetacean bill of rights, listing cetaceans as nonhuman persons. Besides whaling and drive hunting, they also face threats from bycatch and marine pollution. The baiji, for example, is considered functionally extinct by IUCN, with the last sighting in 2004, due to heavy pollution to the Yangtze River. Whales sometimes feature in literature and film, as in the great white sperm whale of Herman Melville's Moby-Dick. Small odontocetes, mainly dolphins, are kept in captivity and trained to perform tricks. Whale watching has become a form of tourism around the world.
Taxonomy
Research history
In Aristotle's time, the fourth century BC, whales were regarded as fish due to their superficial similarity. Aristotle, however, could already see many physiological and anatomical similarities with the terrestrial vertebrates, such as blood (circulation), lungs, uterus, and fin anatomy. His detailed descriptions were assimilated by the Romans, but mixed with a more accurate knowledge of the dolphins, as mentioned by Pliny the Elder in his Natural history. In the art of this and subsequent periods, dolphins are portrayed with a high-arched head (typical of porpoises) and a long snout. The harbor porpoise is one of the most accessible species for early cetologists, because it could be seen very close to land, inhabiting shallow coastal areas of Europe. Many of the findings that apply to all cetaceans were therefore first discovered in the porpoises. One of the first anatomical descriptions of the airways of the whales on the basis of a harbor porpoise dates from 1671 by John Ray. It nevertheless referred to the porpoise as a fish.
Evolution | Toothed whale | Wikipedia | 392 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
Toothed whales, as well as baleen whales, are descendants of land-dwelling mammals of the artiodactyl order (even-toed ungulates). They are closely related to the hippopotamus, sharing a common ancestor that lived around 54 million years ago (mya).
The primitive cetaceans, or archaeocetes, first took to the sea approximately 49 mya and became fully aquatic by 5–10 million years later. The ancestors of toothed whales and baleen whales diverged in the early Oligocene. This was due to a change in the climate of the southern oceans that affected where the environment of the plankton that these whales ate.
The adaptation of echolocation and enhanced fat synthesis in blubber occurred when toothed whales split apart from baleen whales, and distinguishes modern toothed whales from fully aquatic archaeocetes. This happened around 34 mya. Unlike toothed whales, baleen whales do not have wax ester deposits nor branched fatty chain acids in their blubber. Thus, more recent evolution of these complex blubber traits occurred after baleen whales and toothed whales split, and only in the toothed whale lineage.
Modern toothed whales do not rely on their sense of sight, but rather on their sonar to hunt prey. Echolocation also allowed toothed whales to dive deeper in search of food, with light no longer necessary for navigation, which opened up new food sources. Toothed whales (Odontocetes) echolocate by creating a series of clicks emitted at various frequencies. Sound pulses are emitted through the melon-shaped forehead, reflected off objects, and retrieved through the lower jaw. Skulls of Squalodon show evidence for the first hypothesized appearance of echolocation. Squalodon lived from the early to middle Oligocene to the middle Miocene, around 33-14 mya. Squalodon featured several commonalities with modern Odontocetes. The cranium was well compressed, the rostrum telescoped outward (a characteristic of the modern parvorder Odontoceti), giving Squalodon an appearance similar to that of modern toothed whales. However, it is thought unlikely that squalodontids are direct ancestors of living dolphins.
Biology
Anatomy | Toothed whale | Wikipedia | 475 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
Toothed whales have torpedo-shaped bodies with usually inflexible necks, limbs modified into flippers, no outer ears, a large tail fin, and bulbous heads (with the exception of the sperm whale family). Their skulls have small eye orbits, long beaks (with the exception sperm whales), and eyes placed on the sides of their heads. Toothed whales range in size from the and vaquita to the and sperm whale. Overall, they tend to be dwarfed by their relatives, the baleen whales (Mysticeti). Several species have sexual dimorphism, with the females being larger than the males. One exception is with the sperm whale, which has males larger than the females.
Odontocetes possess teeth with cementum cells overlying dentine cells. Unlike human teeth, which are composed mostly of enamel on the portion of the tooth outside of the gum, whale teeth have cementum outside the gum. Only in larger whales, where the cementum is worn away on the tip of the tooth, does enamel show. There is only a single set of functional teeth (monophyodont dentition). Except for the sperm whale, most toothed whales are smaller than the baleen whales. The teeth differ considerably among the species. They may be numerous, with some dolphins bearing over 100 teeth in their jaws. At the other extreme are the narwhals with their single long tusks and the almost toothless beaked whales with tusk-like teeth only in males. In most beaked whales the teeth are seen to erupt in the lower jaw, and primarily occurs at the males sexual maturity. Not all species are believed to use their teeth for feeding. For instance, the sperm whale likely uses its teeth for aggression and showmanship.
Breathing involves expelling stale air from their one blowhole, forming an upward, steamy spout, followed by inhaling fresh air into the lungs. Spout shapes differ among species, which facilitates identification. The spout only forms when warm air from the lungs meets cold air, so it does not form in warmer climates, as with river dolphins. | Toothed whale | Wikipedia | 439 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
Almost all cetaceans have a thick layer of blubber, except for river dolphins. In species that live near the poles, the blubber can be as thick as . This blubber can help with buoyancy, protection to some extent as predators would have a hard time getting through a thick layer of fat, energy for fasting during leaner times, and insulation from the harsh climate. Calves are born with only a thin layer of blubber, but some species compensate for this with thick lanugos.
Toothed whales have also evolved the ability to store large amounts of wax esters in their adipose tissue as an addition to or in complete replacement of other fats in their blubber. They can produce isovaleric acid from branched chain fatty acids (BCFA). These adaptations are unique, are only in more recent, derived lineages and were likely part of the transition for species to become deeper divers as the families of toothed whales (Physeteridae, Kogiidae, and Ziphiidae) that have the highest quantities of wax esters and BCFAs in their blubber are also the species that dive the deepest and for the longest amount of time.
Toothed whales have a two-chambered stomach similar in structure to terrestrial carnivores. They have fundic and pyloric chambers.
Locomotion
Cetaceans have two flippers on the front, and a tail fin. These flippers contain four digits. Although toothed whales do not possess fully developed hind limbs, some, such as the sperm whale, possess discrete rudimentary appendages, which may contain feet and digits. Toothed whales are fast swimmers in comparison to seals, which typically cruise at 5–15 knots, or ; the sperm whale, in comparison, can travel at speeds of up to . The fusing of the neck vertebrae, while increasing stability when swimming at high speeds, decreases flexibility, rendering them incapable of turning their heads; river dolphins, however, have unfused neck vertebrae and can turn their heads. When swimming, toothed whales rely on their tail fins to propel them through the water. Flipper movement is continuous. They swim by moving their tail fin and lower body up and down, propelling themselves through vertical movement, while their flippers are mainly used for steering. Some species log out of the water, which may allow them to travel faster. Their skeletal anatomy allows them to be fast swimmers. Most species have a dorsal fin. | Toothed whale | Wikipedia | 506 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
Most toothed whales are adapted for diving to great depths, porpoises are one exception. In addition to their streamlined bodies, they can slow their heart rate to conserve oxygen; blood is rerouted from tissue tolerant of water pressure to the heart and brain among other organs; haemoglobin and myoglobin store oxygen in body tissue; and they have twice the concentration of myoglobin than haemoglobin. Before going on long dives, many toothed whales exhibit a behaviour known as sounding; they stay close to the surface for a series of short, shallow dives while building their oxygen reserves, and then make a sounding dive.
Senses
Toothed whale eyes are relatively small for their size, yet they do retain a good degree of eyesight. Also, the eyes are on the sides of the head, so their vision consists of two fields, rather than a binocular view as humans have. When a beluga surfaces, its lenses and corneas correct the nearsightedness that results from the refraction of light; they contain both rod and cone cells, meaning they can see in both dim and bright light. They do, however, lack short wavelength-sensitive visual pigments in their cone cells, indicating a more limited capacity for colour vision than most mammals. Most toothed whales have slightly flattened eyeballs, enlarged pupils (which shrink as they surface to prevent damage), slightly flattened corneas, and a tapetum lucidum; these adaptations allow for large amounts of light to pass through the eye, and, therefore, a very clear image of the surrounding area. In water, a whale can see around ahead of itself, but they have a smaller range above water. They also have glands on the eyelids and outer corneal layer that act as protection for the cornea.
The olfactory lobes are absent in toothed whales, and unlike baleen whales, they lack the vomeronasal organ, suggesting they have no sense of smell.
Toothed whales are not thought to have a good sense of taste, as their taste buds are atrophied or missing altogether. However, some dolphins have preferences between different kinds of fish, indicating some sort of attachment to taste.
Echolocation | Toothed whale | Wikipedia | 455 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
Toothed whales are capable of making a broad range of sounds using nasal airsacs located just below the blowhole. Clicks are directional and are used for echolocation, often occurring in a short series called a click train. The click rate increases when approaching an object of interest. Toothed whale biosonar clicks are amongst the loudest sounds made by marine animals.
The cetacean ear has specific adaptations to the marine environment. In humans, the middle ear works as an impedance equalizer between the outside air's low impedance and the cochlear fluid's high impedance. In whales, and other marine mammals, no great difference exists between the outer and inner environments. Instead of sound passing through the outer ear to the middle ear, whales receive sound through the throat, from which it passes through a low-impedance, fat-filled cavity to the inner ear. The ear is acoustically isolated from the skull by air-filled sinus pockets, which allow for greater directional hearing underwater.
Odontocetes generate sounds independently of respiration using recycled air that passes through air sacs and phonic (alternatively monkey) lips. Integral to the lips are oil-filled organs called dorsal bursae that have been suggested to be homologous in the dolphin to the sperm whale's spermaceti organ. These send out high-frequency clicks through the sound-modifying organs of the extramandibular fat body, intramandibular fat body and the melon.
The melon consists of fat, and the skull of any such creature containing a melon will have a large depression. The melon size varies between species, the bigger it is, the more dependent they are on it. A beaked whale, for example, has a small bulge sitting on top of its skull, whereas a sperm whale's head is filled mainly with the melon. Directional asymmetry in the skull has been seen amongst many generations, used for echolocation. This asymmetry is useful in focusing the use of bio sonar effectively when deep diving for prey. Odontocetes are well adapted to hear sounds at ultrasonic frequencies, as opposed to mysticetes who generally hear sounds within the range of infrasonic frequencies.
Communication calls | Toothed whale | Wikipedia | 463 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
Bottlenose dolphins have been found to have signature whistles unique to each individual. Dolphins use these whistles to communicate with one another by identifying an individual. It can be seen as the dolphin equivalent of a name for humans.
Because dolphins generally live in groups, communication is necessary. Signal masking is when other similar sounds (conspecific sounds) interfere with the original sound. In larger groups, individual whistle sounds are less prominent. Dolphins tend to travel in pods, sometimes of up to 600 members.
Life history and behaviour
Intelligence
Cetaceans are known to communicate and therefore are able to teach, learn, cooperate, scheme, and grieve. The neocortex of many species of dolphins is home to elongated spindle neurons that, prior to 2007, were known only in hominids. In humans, these cells are involved in social conduct, emotions, judgement, and theory of mind. Dolphin spindle neurons are found in areas of the brain homologous to where they are found in humans, suggesting they perform a similar function.
Brain size was previously considered a major indicator of the intelligence of an animal. Since most of the brain is used for maintaining bodily functions, greater ratios of brain to body mass may increase the amount of brain mass available for more complex cognitive tasks. Allometric analysis indicates that mammalian brain size scales around the two-thirds or three-quarters exponent of the body mass. Comparison of a particular animal's brain size with the expected brain size based on such allometric analysis provides an encephalization quotient that can be used as another indication of animal intelligence. Sperm whales have the largest brain mass of any animal on earth, averaging and in mature males, in comparison to the average human brain which averages in mature males. The brain to body mass ratio in some odontocetes, such as belugas and narwhals, is second only to humans. | Toothed whale | Wikipedia | 391 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
Dolphins are known to engage in complex play behaviour, which includes such things as producing stable underwater toroidal air-core vortex rings or "bubble rings". Two main methods of bubble ring production are: rapid puffing of a burst of air into the water and allowing it to rise to the surface, forming a ring, or swimming repeatedly in a circle and then stopping to inject air into the helical vortex currents thus formed. They also appear to enjoy biting the vortex rings, so that they burst into many separate bubbles and then rise quickly to the surface. Dolphins are known to use this method during hunting. Dolphins are also known to use tools. In Shark Bay, a population of Indo-Pacific bottlenose dolphins put sponges on their beak to protect them from abrasions and sting ray barbs while foraging in the seafloor. This behaviour is passed on from mother to daughter, and it is only observed in 54 female individuals.
Self-awareness is seen, by some, to be a sign of highly developed, abstract thinking. Self-awareness, though not well-defined scientifically, is believed to be the precursor to more advanced processes like metacognitive reasoning (thinking about thinking) that are typical of humans. Research in this field has suggested that cetaceans, among others, possess self-awareness. The most widely used test for self-awareness in animals is the mirror test, in which a temporary dye is placed on an animal's body, and the animal is then presented with a mirror; then whether the animal shows signs of self-recognition is determined. In 1995, Marten and Psarakos used television to test dolphin self-awareness. They showed dolphins real-time footage of themselves, recorded footage, and another dolphin. They concluded that their evidence suggested self-awareness rather than social behavior. While this particular study has not been repeated since then, dolphins have since "passed" the mirror test.
Vocalisations | Toothed whale | Wikipedia | 396 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
Dolphins make a broad range of sounds using nasal airsacs located just below the blowhole. Roughly three categories of sounds can be identified: frequency modulated whistles, burst-pulsed sounds and clicks. Dolphins communicate with whistle-like sounds produced by vibrating connective tissue, similar to the way human vocal cords function, and through burst-pulsed sounds, though the nature and extent of that ability is not known. The clicks are directional and are for echolocation, often occurring in a short series called a click train. The click rate increases when approaching an object of interest. Dolphin echolocation clicks are amongst the loudest sounds made by marine animals.
Bottlenose dolphins have been found to have signature whistles, a whistle that is unique to a specific individual. These whistles are used in order for dolphins to communicate with one another by identifying an individual. It can be seen as the dolphin equivalent of a name for humans. These signature whistles are developed during a dolphin's first year; it continues to maintain the same sound throughout its lifetime. An auditory experience influences the whistle development of each dolphin. Dolphins are able to communicate to one another by addressing another dolphin through mimicking their whistle. The signature whistle of a male bottlenose dolphin tends to be similar to that of his mother, while the signature whistle of a female bottlenose dolphin tends to be more identifying. Bottlenose dolphins have a strong memory when it comes to these signature whistles, as they are able to relate to a signature whistle of an individual they have not encountered for over twenty years. Research done on signature whistle usage by other dolphin species is relatively limited. The research on other species done so far has yielded varied outcomes and inconclusive results. | Toothed whale | Wikipedia | 350 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
Sperm whales can produce three specific vocalisations: creaks, codas, and slow clicks. A creak is a rapid series of high-frequency clicks that sounds somewhat like a creaky door hinge. It is typically used when homing in on prey. A coda is a short pattern of 3 to 20 clicks that is used in social situations to identify one another (like a signature whistle), but it is still unknown whether sperm whales possess individually specific coda repertoires or whether individuals make codas at different rates. Slow clicks are heard only in the presence of males (it is not certain whether females occasionally make them). Males make a lot of slow clicks in breeding grounds (74% of the time), both near the surface and at depth, which suggests they are primarily mating signals. Outside breeding grounds, slow clicks are rarely heard, and usually near the surface.
Foraging and predation
All whales are carnivorous and predatory. Odontocetes, as a whole, mostly feed on fish and cephalopods, and then followed by crustaceans and bivalves. All species are generalist and opportunistic feeders. Some may forage with other kinds of animals, such as other species of whales or certain species of pinnipeds. One common feeding method is herding, where a pod squeezes a school of fish into a small volume, known as a bait ball. Individual members then take turns plowing through the ball, feeding on the stunned fish. Coralling is a method where dolphins chase fish into shallow water to catch them more easily. Orcas and bottlenose dolphins have also been known to drive their prey onto a beach to feed on it, a behaviour known as beach or strand feeding. The shape of the snout may correlate with tooth number and thus feeding mechanisms. The narwhal, with its blunt snout and reduced dentition, relies on suction feeding. | Toothed whale | Wikipedia | 397 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
Sperm whales usually dive between , and sometimes , in search of food. Such dives can last more than an hour. They feed on several species, notably the giant squid, but also the colossal squid, octopuses, and fish like demersal rays, but their diet is mainly medium-sized squid. Some prey may be taken accidentally while eating other items. A study in the Galápagos found that squid from the genera Histioteuthis (62%), Ancistrocheirus (16%), and Octopoteuthis (7%) weighing between were the most commonly taken. Battles between sperm whales and giant squid or colossal squid have never been observed by humans; however, white scars are believed to be caused by the large squid. A 2010 study suggests that female sperm whales may collaborate when hunting Humboldt squid.
The orca is known to prey on numerous other toothed whale species. One example is the false killer whale. To subdue and kill whales, orcas continually ram them with their heads; this can sometimes kill bowhead whales, or severely injure them. Other times, they corral their prey before striking. They are typically hunted by groups of 10 or fewer orca, but they are seldom attacked by an individual. Calves are more commonly taken by orca, but adults can be targeted, as well. Groups even attack larger cetaceans such as minke whales, gray whales, and rarely sperm whales or blue whales. Other marine mammal prey species include nearly 20 species of seal, sea lion and fur seal.
These cetaceans are targeted by terrestrial and pagophilic predators. The polar bear is well-adapted for hunting Arctic whales and calves. Bears are known to use sit-and-wait tactics, as well as active stalking and pursuit of prey on ice or water. Whales lessen the chance of predation by gathering in groups. This, however, means less room around the breathing hole as the ice slowly closes the gap. When out at sea, whales dive out of the reach of surface-hunting orca. Polar bear attacks on belugas and narwhals are usually successful in winter, but rarely inflict any damage in summer. | Toothed whale | Wikipedia | 451 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
For most of the smaller species of dolphins, only a few of the larger sharks, such as the bull shark, dusky shark, tiger shark, and great white shark, are a potential risk, especially for calves. Dolphins can tolerate and recover from extreme injuries (including shark bites) although the exact methods used to achieve this are not known. The healing process is rapid and even very deep wounds do not cause dolphins to hemorrhage to death. Even gaping wounds restore in such a way that the animal's body shape is restored, and infection of such large wounds are rare.
Life cycle
Toothed whales are fully aquatic creatures, which means their birth and courtship behaviours are very different from terrestrial and semiaquatic creatures. Since they are unable to go onto land to calve, they deliver their young with the fetus positioned for tail-first delivery. This prevents the calf from drowning either upon or during delivery. To feed the newborn, toothed whales, being aquatic, must squirt the milk into the mouth of the calf. Being mammals, they have mammary glands used for nursing calves; they are weaned around 11 months of age. This milk contains high amounts of fat which is meant to hasten the development of blubber; it contains so much fat, it has the consistency of toothpaste. Females deliver a single calf, with gestation lasting about a year, dependency until one to two years, and maturity around seven to 10 years, all varying between the species. This mode of reproduction produces few offspring, but increases the survival probability of each one. Females, referred to as "cows", carry the responsibility of childcare, as males, referred to as "bulls", play no part in raising calves.
In orcas, false killer whales, short-finned pilot whales, narwhals, and belugas, there is an unusually long post-reproductive lifespan (menopause) in females. Older females, though unable to have their own children, play a key role in the rearing of other calves in the pod, and in this sense, given the costs of pregnancy especially at an advanced age, extended menopause is advantageous.
Interaction with humans
Threats
Sperm whaling | Toothed whale | Wikipedia | 455 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
The head of the sperm whale is filled with a waxy liquid called spermaceti. This liquid can be refined into spermaceti wax and sperm oil. These were much sought after by 18th-, 19th-, and 20th-century whalers. These substances found a variety of commercial applications, such as candles, soap, cosmetics, machine oil, other specialized lubricants, lamp oil, pencils, crayons, leather waterproofing, rustproofing materials, and many pharmaceutical compounds.
Ambergris, a solid, waxy, flammable substance produced in the digestive system of sperm whales, was also sought as a fixative in perfumery.
Sperm whaling in the 18th century began with small sloops carrying only a pair of whaleboats (sometimes only one). As the scope and size of the fleet increased, so did the rig of the vessels change, as brigs, schooners, and finally ships and barks were introduced. In the 19th-century stubby, square-rigged ships (and later barks) dominated the fleet, being sent to the Pacific (the first being the British whaleship Emilia, in 1788), the Indian Ocean (1780s), and as far away as the Japan grounds (1820) and the coast of Arabia (1820s), as well as Australia (1790s) and New Zealand (1790s).
Hunting for sperm whales during this period was notoriously dangerous for the crews of the 19th-century whaleboats. Though a properly harpooned sperm whale generally exhibited a fairly consistent pattern of trying to flee underwater to the point of exhaustion (at which point it would surface and offer no further resistance), it was not uncommon for bull whales to become enraged and turn to attack pursuing whaleboats on the surface, particularly if it had already been wounded by repeated harpooning attempts. A commonly reported tactic was for the whale to invert itself and violently thrash the surface of the water with its fluke, flipping and crushing nearby boats. | Toothed whale | Wikipedia | 408 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
The estimated historic worldwide sperm whale population numbered 1,100,000 before commercial sperm whaling began in the early 18th century. By 1880, it had declined an estimated 29%. From that date until 1946, the population appears to have recovered somewhat as whaling pressure lessened, but after the Second World War, with the industry's focus again on sperm whales, the population declined even further to only 33%. In the 19th century, between 184,000 and 236,000 sperm whales were estimated to have been killed by the various whaling nations, while in the modern era, at least 770,000 were taken, most between 1946 and 1980. Remaining sperm whale populations are large enough so that the species' conservation status is vulnerable, rather than endangered. However, the recovery from the whaling years is a slow process, particularly in the South Pacific, where the toll on males of breeding age was severe.
Drive hunting
Dolphins and porpoises are hunted in an activity known as dolphin drive hunting. This is done by driving a pod together with boats and usually into a bay or onto a beach. Their escape is prevented by closing off the route to the ocean with other boats or nets. Dolphins are hunted this way in several places around the world, including the Solomon Islands, the Faroe Islands, Peru, and Japan, the most well-known practitioner of this method. By numbers, dolphins are mostly hunted for their meat, though some end up in dolphinariums. Despite the controversial nature of the hunt resulting in international criticism, and the possible health risk that the often polluted meat causes, thousands of dolphins are caught in drive hunts each year. | Toothed whale | Wikipedia | 329 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
In Japan, the hunting is done by a select group of fishermen. When a pod of dolphins has been spotted, they are driven into a bay by the fishermen while banging on metal rods in the water to scare and confuse the dolphins. When the dolphins are in the bay, it is quickly closed off with nets so the dolphins cannot escape. The dolphins are usually not caught and killed immediately, but instead left to calm down over night. The following day, the dolphins are caught one by one and killed. The killing of the animals used to be done by slitting their throats, but the Japanese government banned this method, and now dolphins may officially only be killed by driving a metal pin into the neck of the dolphin, which causes them to die within seconds according to a memo from Senzo Uchida, the executive secretary of the Japan Cetacean Conference on Zoological Gardens and Aquariums. A veterinary team's analysis of a 2011 video footage of Japanese hunters killing striped dolphins using this method suggested that, in one case, death took over four minutes.
Since much of the criticism is the result of photos and videos taken during the hunt and slaughter, it is now common for the final capture and slaughter to take place on site inside a tent or under a plastic cover, out of sight from the public. The most circulated footage is probably that of the drive and subsequent capture and slaughter process taken in Futo, Japan, in October 1999, shot by the Japanese animal welfare organization Elsa Nature Conservancy. Part of this footage was, amongst others, shown on CNN. In recent years, the video has also become widespread on the internet and was featured in the animal welfare documentary Earthlings, though the method of killing dolphins as shown in this video is now officially banned. In 2009, a critical documentary on the hunts in Japan titled The Cove was released and shown amongst others at the Sundance Film Festival. | Toothed whale | Wikipedia | 384 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
Other threats
Toothed whales can also be threatened by humans more indirectly. They are unintentionally caught in fishing nets by commercial fisheries as bycatch and accidentally swallow fishhooks. Gillnetting and Seine netting are significant causes of mortality in cetaceans and other marine mammals. Porpoises are commonly entangled in fishing nets. Whales are also affected by marine pollution. High levels of organic chemicals accumulate in these animals since they are high in the food chain. They have large reserves of blubber, more so for toothed whales, as they are higher up the food chain than baleen whales. Lactating mothers can pass the toxins on to their young. These pollutants can cause gastrointestinal cancer and greater vulnerability to infectious diseases. They may also swallow litter, such as plastic bags. Pollution of the Yangtze river has led to the extinction of the baiji. Environmentalists speculate that advanced naval sonar endangers some whales. Some scientists suggest that sonar may trigger whale beachings, and they point to signs that such whales have experienced decompression sickness.
Conservation
Currently, no international convention gives universal coverage to all small whales, although the International Whaling Commission has attempted to extend its jurisdiction over them. ASCOBANS was negotiated to protect all small whales in the North and Baltic Seas and in the northeast Atlantic. ACCOBAMS protects all whales in the Mediterranean and Black Seas. The global UNEP Convention on Migratory Species currently covers seven toothed whale species or populations on its Appendix I, and 37 species or populations on Appendix II. All oceanic cetaceans are listed in CITES appendices, meaning international trade in them and products derived from them is very limited.
Many organizations are dedicated to protecting certain species that do not fall under any international treaty, such as CIRVA (Committee for the Recovery of the Vaquita), and the Wuhan Institute of Hydrobiology (for the Yangtze finless porpoise).
In captivity
Species | Toothed whale | Wikipedia | 405 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
Various species of toothed whales, mainly dolphins, are kept in captivity, as well as several other species of porpoise such as harbour porpoises and finless porpoises. These small cetaceans are more often than not kept in theme parks, such as SeaWorld, commonly known as a dolphinarium. Bottlenose dolphins are the most common species kept in dolphinariums, as they are relatively easy to train, have a long lifespan in captivity, and have a friendly appearance. Hundreds if not thousands of bottlenose dolphins live in captivity across the world, though exact numbers are hard to determine. Orca are well known for their performances in shows, but the number kept in captivity is very small, especially when compared to the number of bottlenose dolphins, with only 44 captives being held in aquaria as of 2012. Other species kept in captivity are spotted dolphins, false killer whales, and common dolphins, Commerson's dolphins, as well as rough-toothed dolphins, but all in much lower numbers than the bottlenose dolphin. Also, fewer than ten pilot whales, Amazon river dolphins, Risso's dolphins, spinner dolphins, or tucuxi are in captivity. Two unusual and very rare hybrid dolphins, known as wolphins, are kept at the Sea Life Park in Hawaii, which is a cross between a bottlenose dolphin and a false killer whale. Also, two common/bottlenose hybrids reside in captivity: one at Discovery Cove and the other at SeaWorld San Diego.
Controversy
Organizations such as the Animal Welfare Institute and Whale and Dolphin Conservation campaign against the captivity of dolphins and orcas. SeaWorld faced a lot of criticism after the documentary Blackfish was released in 2013. | Toothed whale | Wikipedia | 355 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
Aggression among captive orca is common. In August 1989, a dominant female orca, Kandu V, tried to rake a newcomer whale, Corky II, with her mouth during a live show, and smashed her head into a wall. Kandu V broke her jaw, which severed an artery, and then bled to death. In November 2006, a dominant female killer whale, Kasatka, repeatedly dragged experienced trainer Ken Peters to the bottom of the stadium pool during a show after hearing her calf crying for her in the back pools. In February 2010, an experienced female trainer at SeaWorld Orlando, Dawn Brancheau, was killed by orca Tilikum shortly after a show in Shamu Stadium. Tilikum had been associated with the deaths of two people previously. In May 2012, Occupational Safety and Health Administration administrative law judge Ken Welsch cited SeaWorld for two violations in the death of Dawn Brancheau and fined the company a total of US$12,000. Trainers were banned from making close contact with the orca. In April 2014, the US Court of Appeals for the District of Columbia denied an appeal by SeaWorld.
In 2013, SeaWorld's treatment of orca in captivity was the basis of the movie Blackfish, which documents the history of Tilikum, an orca captured by SeaLand of the Pacific, later transported to SeaWorld Orlando, which has been involved in the deaths of three people. In the aftermath of the release of the film, Martina McBride, 38 Special, REO Speedwagon, Cheap Trick, Heart, Trisha Yearwood, and Willie Nelson cancelled scheduled concerts at SeaWorld parks. SeaWorld disputes the accuracy of the film, and in December 2013 released an ad countering the allegations and emphasizing its contributions to the study of cetaceans and their conservation. | Toothed whale | Wikipedia | 371 | 326837 | https://en.wikipedia.org/wiki/Toothed%20whale | Biology and health sciences | Toothed whale | Animals |
Draco is a genus of agamid lizards that are also known as flying lizards, flying dragons or gliding lizards. These lizards are capable of gliding flight via membranes that may be extended to create wings (patagia), formed by an enlarged set of ribs. They are arboreal insectivores.
While not capable of powered flight they often obtain lift in the course of their gliding flights. Glides as long as have been recorded, over which the animal loses only in height which makes for a glide ratio of 6:1. This is done by a lizard of only around in total length, tail included. They are found across Southeast Asia and Southern India and are fairly common in forests, areca gardens, teak plantations and shrub jungle.
History of discovery
Carl Linnaeus described the genus in 1758, with the type species being Draco volans. The name of the genus is from the Latin term for dragons of mythology. In the early and mid 20th century, there was controversy about their gliding capabilities, with some authors suggesting that the patagia were solely for display, but research in the late 1950s firmly established the gliding function of the patagia.
Distribution
Species of Draco are widely distributed in the forests of Southeast Asia, with one species, Draco dussumieri, inhabiting Southern India.
Habitat and ecology
Members of Draco are primarily arboreal, inhabiting tropical rainforests, and are almost never found on the forest floor. They are insectivorous, primarily feeding on eusocial insects such as ants and termites. The colour of the patagium is strongly correlated to the colour of falling leaves in their range, which complements their cryptic camouflage resembling tree bark; both are likely to be camouflage against predatory birds.
Gliding | Draco (lizard) | Wikipedia | 354 | 326872 | https://en.wikipedia.org/wiki/Draco%20%28lizard%29 | Biology and health sciences | Iguania | Animals |
The lizards are well known for their "display structures" and ability to glide long distances using their wing-like, patagial membranes supported by elongated thoracic ribs to generate lift forces. The hindlimbs in cross section form a streamlined and contoured airfoil, and are also probably involved in generating lift. Gliding is both used to escape predators, and as the primary means of moving through their forest habitat. The folding and unfolding of the membrane is controlled by the iliocostalis and intercostal muscles, which in other lizards are used to control breathing. At takeoff, the lizard jumps and descends headfirst, orientating itself so that the underside of the body is parallel to the ground. During flight, the back arches, forming the patagium into a cambered surface, and the forelimbs grab the front of the patagium, forming a straight front edge to the aerofoil. The forelimbs are used to manipulate the patagium in order to adjust the trajectory during flight. Maximum gliding speeds have been found to be between 5.2 and 7.6 metres per second, depending on the species. During the landing process, the glide is mostly horizontal. Immediately before landing, the forelimbs release the patagium. The landing is forefeet-first, followed by hindfeet. The shape of the gliding membrane does not correlate with body size, meaning the larger species have proportionately less lift-generating surface area and consequently higher wing loading. | Draco (lizard) | Wikipedia | 308 | 326872 | https://en.wikipedia.org/wiki/Draco%20%28lizard%29 | Biology and health sciences | Iguania | Animals |
Life history
Draco lizards are highly territorial, with the home range consisting of one or a few trees. The trees are actively guarded by males, with territory-less males searching the forest landscape in search of vacant areas. Experimental studies have determined that suitable unoccupied territories were claimed within a few hours of the removal of a dominant male. Females move freely through the territories. The patagium is used as a display structure during courtship and territorial disputes between rival males, alongside the opening of a brightly-colored dewlap that contrasts with their camouflaged body scalation. The dewlap is translucent, and deliberately orientated perpendicular to the orientation of the sun during display in order to enhance visibility. Draco is sexually dimorphic, with females being larger than males. The only time a female flying lizard ventures to the ground is when she is ready to lay her eggs. She descends the tree she is on and makes a nest hole by forcing her head into the soil. She then lays a clutch of 2–5 eggs before filling the hole and guards the eggs for approximately 24 hours, but then leaves and has nothing more to do with her offspring.
Phylogenetics
Within Agamidae, Draco is a member of the subfamily Draconinae. Within Draconinae, Draco is most closely related to the genera Japalura and Ptyctolaemus.
Species
The following 41 species are recognized: | Draco (lizard) | Wikipedia | 288 | 326872 | https://en.wikipedia.org/wiki/Draco%20%28lizard%29 | Biology and health sciences | Iguania | Animals |
Draco abbreviatus – Singapore flying dragon
Draco beccarii
Draco biaro – Lazell's flying dragon
Draco bimaculatus – two-spotted flying lizard
Draco blanfordii – Blanford's flying dragon, Blanford’s flying lizard, Blanford's gliding lizard
Draco boschmai
Draco caerulhians
Draco cornutus
Draco cristatellus – crested flying dragon
Draco cyanopterus
Draco dussumieri – Indian flying lizard, Western Ghats flying lizard, southern flying lizard
Draco fimbriatus – fringed flying dragon, crested gliding lizard
Draco formosus – dusky gliding lizard
Draco guentheri – Günther's flying lizard, Guenther's flying lizard
Draco haematopogon – red-bearded flying dragon, yellow-bearded gliding lizard
Draco indochinensis – Indochinese flying lizard, Indochinese gliding lizard
Draco iskandari
Draco jareckii
Draco lineatus – lined flying dragon
Draco maculatus – spotted flying dragon
Draco maximus – great flying dragon, giant gliding lizard
Draco melanopogon – black-bearded gliding lizard, black-barbed flying dragon
Draco mindanensis – Mindanao flying dragon, Mindanao flying lizard
Draco modiglianii – lined flying dragon
Draco norvillii – Norvill's flying lizard
Draco obscurus – dusky gliding lizard
Draco ornatus – white-spotted flying lizard
Draco palawanensis
Draco punctatus – punctate flying dragon
Draco quadrasi – Quadras's flying lizard
Draco quinquefasciatus – five-lined flying dragon, five-banded gliding lizard
Draco reticulatus
Draco rhytisma
Draco spilonotus – Sulawesi lined gliding lizard
Draco spilopterus – Philippine flying dragon
Draco sumatranus – common gliding lizard
Draco supriatnai
Draco taeniopterus – Thai flying dragon, barred flying dragon, barred gliding lizard
Draco timoriensis – Timor flying dragon
Draco volans – common flying dragon
Draco walkeri
Nota bene: a binomial authority in parentheses indicates that the species was originally described in a genus other than Draco. | Draco (lizard) | Wikipedia | 476 | 326872 | https://en.wikipedia.org/wiki/Draco%20%28lizard%29 | Biology and health sciences | Iguania | Animals |
Similar prehistoric reptiles
Several other lineages of reptile known from the fossil record have convergently evolved similar gliding mechanisms consisting of a patagium or plate flanking the torso; the weigeltisaurids are the oldest of these, living in the Late Permian from around 258 to 252 million years ago. Other lineages include the Triassic kuehneosaurids and Mecistotrachelos, and the Cretaceous lizard Xianglong. | Draco (lizard) | Wikipedia | 88 | 326872 | https://en.wikipedia.org/wiki/Draco%20%28lizard%29 | Biology and health sciences | Iguania | Animals |
Hydrosaurus, commonly known as the sailfin dragons or sailfin lizards, is a genus in the family Agamidae. These relatively large lizards are named after the sail-like structure on their tails. They are native to Indonesia (4 species) and the Philippines (1 species) where they are generally found near water, such as rivers and mangrove. Sailfin lizards are semiaquatic and able to run short distances across water using both their feet and tail for support, similar to the basilisks. They are threatened by both habitat loss and overcollection for the wild animal trade.
In the 19th century, the genus was called Lophura, however in 1903 Poche pointed out that the name was pre-occupied by a genus of pheasants. Since Günther in 1873, the Sulawesi populations were considered to belong to H. amboinensis; Denzer et al. in 2020 resurrected H. celebensis and H. microlophus, increasing the number of species from three to five.
They are the only members of the subfamily Hydrosaurinae.
Species
There are currently five valid species according to the Reptile Database, | Hydrosaurus | Wikipedia | 234 | 326877 | https://en.wikipedia.org/wiki/Hydrosaurus | Biology and health sciences | Iguania | Animals |
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