Page "Daphnia" Paragraph 9

Daphnia spp.

reproduce parthenogenetically usually in the spring until the end of the summer.

One or more juvenile animals are nurtured in the brood pouch inside the carapace.

Newly hatched Daphnia must molt several times before they are fully grown into adults, usually after about two weeks.

The young are small copies of the adult ; there are no true nymphal or instar stages.

The fully mature females are able to produce a new brood of young about every ten days under ideal conditions.

The reproduction process continues while the environmental conditions continue to support their growth.

When winter approaches, in drought conditions, or at times of other harsh environmental conditions, production of new female generations ceases and parthenogenic males are produced.

However, even in harsh environmental conditions, males may make up considerably less than half the population ; in some species, they are unknown entirely.

Males are much smaller in size than the females, and they typically possess a specialized abdominal appendage which is used in mating to grasp a female from behind, pry open her carapace, insert a spermatheca, and thus fertilize the eggs.