Question

why aquatic animals release hundred of eggs and millions of sperms?

Answer 1

They are protandric; during their first year they spawn as males by releasing sperminto the water. ... An increase in watertemperature prompts a few oysters to spawn. This triggers spawning in the rest, clouding the water with millions of eggsand sperm. A single female oyster canproduce up to 100 million eggs annually

Answer 2

Most of the eggs of aquatic animals get eaten away by other aquatic animals like fishes.They produce many eggs and sperms in order to ensure that at least some of them get fertilised and produce new individuals.