Chapter 40 Amphibians Section 3 Reproduction in Amphibians.
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Transcript of Chapter 40 Amphibians Section 3 Reproduction in Amphibians.
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.