Chapter 40 Amphibians Section 3 Reproduction in Amphibians

Reproduction Compare and contrast terrestrial vs. aquatic reproduction.

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

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

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

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

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)

Axolotl

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

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

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

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.