Chapter 40 Amphibians

1. Chapter 40Amphibians Section 3 Reproduction in Amphibians

2. Reproduction • Compare and contrast terrestrial vs. aquatic reproduction.

3. Courtship & Fertilization • First warm days of spring, amphibians emerge and head towards water • Males call to attract females of own species and warn off other males • Females only respond to a call from a male of the same species

4. Courtship & Fertilization • Females approach males, and males climb onto female’s back • Males grasps female firmly in an embrace called amplexus • Male clings to female until she lays eggs, then he fertilizes them externally

6. Reproductive System • Male- two bean shaped testes near kidneys, sperm leave through cloaca • Female- ovaries containing thousands of tiny immature eggs that lie near kidneys, eggs pass through cloaca

8. Life Cycle • Metamorphosis- fertilized eggs  hatching tadpole  hind legs appear  front legs appear  tail disappears  young adult  adult • Hormone thyroxine triggers metamorphosis

11. Life Cycle • Some amphibians don’t lay eggs in water, lay eggs in moist areas • One or both parents might construct a nest for amphibians • Not all amphibians undergo metamorphosis- axolotl- larval stage entire life (salamander)

12. Axolotl

13. Parental Care • Increases likelihood of offspring survival • Male usually stays with eggs and voids off predators

14. Parental Care • Male Darwin’s frog of Chile takes the eggs into vocal sacs, they hatch and undergo metamorphosis- climb out of vocal sacs and emerge from male’s mouth

16. Parental Care • Female gastric-brooding frogs of Australia swallow eggs which hatch and mature in the stomach • Not digested because stomach stops producing acid and digestive enzymes until young are released

18. REVIEW!!! • Identify two functions of the male frog’s call. • Sequence the stages of a frog’s life cycle. • Name the hormone responsible for stimulating tadpoles to undergo metamorphosis.