Chapter 40Amphibians

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.