1. Class Amphibia
The Tetrapods

2. Fig. 25.2

3. Fig. 25.3

4. Moving Ashore

5. Transitional Forms
Fig. 25.1a

6. Early Land Tetrapods
Fig. 25.1b

7. Evolutionary Lung Forms

8. Changes in Lung Anatomy In Tetrapods

9. Amphibian Respiration

10. Changes in Vertebrate Circulatory Systems

11. Amphibian Heart Anatomy
Fig

12. General Amphibian Traits
Tetrapods
3-5 digits on forelimb (most 4)
5 digits on hind limb
No dermal scales
Glandular epidermis
Most with indirect development, some with tadpole larvae
Gills as larvae/juveniles, lungs present but may degenerate, some with dermal respiration

13. Order Gymnophiona
~160 species
Legless
Burrowing or aquatic
Tropical
Internal fertilization
Oviparous & viviparous species
Direct development in most

14. Order Gymnophiona (Apoda)
Caecilians
Fig. 25.5

15. Order Caudata (Urodela)
AKA Salamanders
Have a tail
Divergence in respiratory mechanisms
Paedomorphosis prevalent
Internal fertilization

16. Salamander/Newt Lifecycle
Fig. 25.8

17. Some Urodeles Necturus maculosus Giant Japanese Salamander
Southern dusky salamander
Ambystoma mexicanum
(Axolotl)
Fig. 25.9

18. Order Anura Frogs & Toads No tail External fertilization
Indirect development in most
Fig b

19. Frog or Toad? Frogs Toads Associated with more aquatic habitats
Thicker skins
Dryer habitats
Fig

20. Her Royal Highness Xenopus laevis Developmental model system
Fig

21. Typical Anuran Lifecycle
Fig

22. Really Weird Surinam Toad

24. Local Species Acris crepitans Rana catesbeiana Bufo speciosus
Bufo woodhousii
Pseudacris clarki
Rana pipiens