Frog Reproduction zoology

Objectives Explain how male frogs attracts females of the same species. Discuss the reproductive system of a frog. Describe the changes that occur during metamorphosis. Identify two examples of parental care in frogs.

Courtship Each species has a call that is specific to that species. Males call to attract a mate. Air is driven back and forth from mouth to lungs to vibrate vocal cords. Females respond only to males of the same species.

Fertilization When female approaches, the male climbs onto her back. He grasps her firmly. This embrace is called an amplexus. The female releases her eggs and the male deposits his sperm on top of them. Direct external fertilization is achieved.

Reproductive System Male has two bean shaped testes located near the kidneys. Sperm is passed from the testes in a tube and exits through the cloacal opening. Female produces eggs in lobed ovaries near the kidneys. Eggs leave through the cloaca.

Life Cycle Eggs hatch into tadpoles within a few days of fertilization. Tadpoles live off of the yolk of the egg for a few days until the mouth opens and gills are grown. Metamorphosis begins.

Metamorphosis Hatchling tadpoles Hind legs appear Front legs appear Tale disappears Young Frog grows to adult size. Controlled by the hormone thyroxine.

Alternative methods Lay eggs on land Lay eggs in mucus Bypass larval stage

Parental Care Increase the likelihood that offspring survive. Male often remains with eggs to guard them. Some males hold eggs in their mouth until they hatch. Females gastric brood eggs.