Reproduction

Sexes are separate and females brood eggs in the chamber of the carapace. The male must tranfer sperm to the female before the eggs are laid and a special long leg is used to do this. Males of some species attract females using flashing lights to signal, like Morse Code. The females can distinguish between related species because each has its own individual pattern. In spite of being quite small animals ostracods can live for more than two years but moult only four or five times. Females of some freshwater ostracods lay eggs without the benefit of males.

Ecology

Most of the many species of ostracods are aquatic but rare examples are terrestrial in damp places in Australian forests. In the sea where the group is most diverse ostracods walk about on the surface of the sand on the legs slightly protruding from between the shells of the carapace. On marine sediments some families of ostracods are important components of the scavenging community, cleaning up dead fish. Others are micro-predators and have strong claws for grabbing small living prey. Some species are brilliantly luminescent.

Distribution

Ostracods are found in most habitats but are especially abundant and rich in the sea. Most species live on the sea floor but a few are planktonic. Some live in lakes and streams and there are rare examples in damp places on land.