# Zoology: The Animal Kingdom

## 🧬 Classification (Taxonomy)
- **Domain**: Eukaryota
- **Kingdom**: Animalia
- **Phyla**: Chordata (Vertebrates), Arthropoda (Insects/Crustaceans), Mollusca, etc.

## 🦁 Mammalia
- **Monotremes**: Egg-laying mammals (Platypus).
- **Marsupials**: Pouch-rearing (Kangaroo, Opossum).
- **Placentals**: Internal development (Humans, Lions, Whales).

## 🦅 Aves (Birds)
- **Evolution**: Modern descendants of theropod dinosaurs.
- **Adaptations**: Hollow bones, feathers, and high-metabolic flight systems.

## 🦈 Chondrichthyes & Osteichthyes (Fish)
- **Cartilaginous**: Sharks and rays.
- **Bony**: Salmon, tuna, and most reef fish.

## 🐍 Reptilia & Amphibia
- **Ectotherms**: Regulation of body temperature via external sources.
- **Amphibians**: Dual-life (water-based larvae, terrestrial adults).

## 🐝 Invertebrates
- **Success**: Arthropods account for over 80% of all described animal species.
- **Roles**: Pollination, decomposition, and foundational food web support.