Amphibians reproduce sexually with either external or internal fertilization. They may attract mates with calls or scents and lay hundreds of eggs at a time, as very few will survive to adulthood and breed themselves. Reproduction involves the fusion of eggs produced in female ovaries, and sperms generated by male testes.
Different reproductive modes are seen in amphibians, such as depositing eggs in foam nests which float on water; laying eggs on the back of the female; and producing spermatozoa and reproductive behavior in males. The young undergo an aquatic larval stage before emerging on land as adults.
Reproductive Strategies
A large number of eggs are laid in a lentic water body and externally fertilized. Progesterone promotes the maturation of oocytes and ovulation while hormones control reproduction behaviours in females.
Evolutionary Changes
Amphibian reproductive modes are traditionally thought to have evolved sequentially with only single ontogenetic modules (life stages) changing over time. This has led to a wide variety of life cycles among amphibians that have adapted to different environments over time.
Uses for Humans
Amphibians are economically useful because they reduce the number of insects that can damage crops, thus providing natural pest control for farmers. Additionally, amphibians provide food sources for humans, particularly in tropical areas where frogs are commonly eaten.
