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.