Chapter 40 Amphibians

1. Chapter 40Amphibians Section 1 Origin and Evolution of Amphibians

2. Amphibians • Greek word meaning “double” and “life” • Many amphibians spend part of their life in water and part on land

3. Adaptation to Land • Most likely evolved from lobe-finned fishes • Pre-adaptations- adaptations in an ancestral group that allow a shift to new functions which are later favored by natural selection

4. Adaptation to Land • Lobe-finned fish ancestral amphibians- appendages to walk • Had modified pouches in their digestive tract that evolved into lungs • Had nostrils to help aid in breathing on land

5. Characteristics of Early Amphibians • Amphibians and lobe-finned fishes share many similarities: skull & vertebral column • Sarcopterygian- extinct lobe-finned fish that is thought to be closely related to amphibians

6. Sarcopterygian

7. Diversification of Amphibians • 4,500 species belonging to three orders • Anura- frogs and toads • Caudata- salamanders • Gymnophiona- caecilians- legless tropical amphibians

9. Modern Amphibians • Most change from aquatic larval stage to a terrestrial adult form- metamorphosis • Most have moist, thin skin with no scales • Feet, if present, lack claws and often are webbed

10. Modern Amphibians • Most use gills, lungs, and skin respiration • Eggs lack multi-cellular membranes or shells. They are usually laid in water or in moist places and are usually fertilized externally

11. Order Anura • Frogs & toads • World-wide, except in polar climates and a few oceanic islands • Either spend part of or entire live in water • Toad- rough, bumpy skin • Frog- smooth, moist skin

12. Order Anura • Body adapted for jumping (long muscular legs) • Adult anurans are carnivores • Have a sticky tongue to help capture food • Return to water to reproduce • Tadpoles- fertilized eggs hatch into swimming, tailed larva

13. Poison Dart Frog

14. Gray Tree Frog

15. Bull Frog

16. Leopard Frog

17. Cane Toad

18. American Toad

19. Order Caudata • Salamanders- elongated bodies, long tails, and moist skin • Smallest are only a few centimeters long, largest are over 4.5 feet • Aquatic and terrestrial species • Carnivores

20. Order Caudata • Most live in North America and Central America • Some are lungless and breathe through their skin • Some reproduce in water, while others lay eggs on land

21. Order Caudata • Water reproduction- larval stage • Land reproduction- no larval stage • Internal fertilization • Some terrestrial species stay with eggs until hatched

22. Spring Salamander

23. Dusky Salamander

24. Red-Spotted Newt

25. Spotted Salamander

26. Order Gymnophiona • Caecilian- legless amphibian- resembles snakes • Found in tropical areas of Asia, Africa, and South America • 12 inches to 4.5 feet • Often are blind because their eyes are found under skin and bone

27. Order Gymnophiona • Rarely seen- little is known • Some burrow and some are aquatic • Have teeth- eat worms and other invertebrates

28. Order Gymnophiona • Internal fertilization • Some species lay eggs & some are born live • Young use their jaws and teeth to scrape secretions “uterine milk” from the walls of the female’s reproduction tract

29. Sagalla Caecilian

30. Purple Caecilian

31. REVIEW!!! • Name some characteristics that are common to modern amphibians. • Compare and contrast the three living orders of amphibians.