Introduction to Vertebrates
Five major classes of vertebrates showing progressive adaptation from water to land:
- Pisces (Fish)
- Amphibians
- Reptiles
- Aves (Birds)
- Mammals
Vertebrate Classes Comparison
| Feature | Pisces | Amphibians | Reptiles | Aves | Mammals |
|---|---|---|---|---|---|
| Body covering | Scales | Moist skin | Dry scales | Feathers | Hair/Fur |
| Temperature regulation | Cold-blooded | Cold-blooded | Cold-blooded | Warm-blooded | Warm-blooded |
| Respiration | Gills | Gills (larva) + Lungs (adult) | Lungs | Lungs + Air sacs | Lungs |
| Heart chambers | 2 chambers | 3 chambers | 3 chambers (4 in crocodiles) | 4 chambers | 4 chambers |
| Reproduction | External fertilization | External fertilization | Internal fertilization | Internal fertilization | Internal fertilization |
| Eggs | Jelly-coated | Jelly-coated | Leathery shell | Hard calcareous shell | No eggs (live birth) |
| Limbs | Fins | 4 limbs | 4 limbs (absent in snakes) | 2 legs + 2 wings | 4 limbs |
| Habitat | Aquatic | Aquatic + Terrestrial | Terrestrial | Terrestrial + Aerial | Terrestrial (some aquatic) |
| Examples | Shark, Salmon, Goldfish | Frog, Toad, Salamander | Snake, Lizard, Turtle | Sparrow, Eagle, Penguin | Human, Whale, Bat |
3. Pisces (Fish)
Aquatic vertebrates adapted for life in water
- Streamlined body
- Gill respiration
- Fins for locomotion
- Scales covering
- 2-chambered heart
- Cold-blooded
- External fertilization
🐟 Fish Anatomy - Interactive Learning
🐟 Fish Structure
📚 Function Information
Click on any label to see its function and characteristics!
4. Amphibians
Animals with dual life - aquatic larvae and terrestrial adults
- Dual habitat
- Skin respiration
- Metamorphosis
- 3-chambered heart
- Aquatic reproduction
- Tetrapod limbs
- Common amphibians
5. Reptiles
First truly terrestrial vertebrates with dry scaly skin
- Waterproof skin
- Amniotic eggs
- Internal fertilization
- Pulmonary respiration
- Advanced heart
- Ectothermic
- Reptile diversity
6. Aves (Birds)
Warm-blooded animals adapted for flight
- Feathers
- Wings
- Warm-blooded
- Pneumatic bones
- Complete heart division
- Enhanced respiration
- Calcareous eggs
7. Mammals
Most advanced vertebrates with maternal care
- Hair or fur
- Mammary glands
- Viviparous
- Endothermic
- Advanced circulation
- Large cerebrum
- Neck vertebrae