O stracods are sometimes called mussel or seed shrimps and are small crustaceans that are widely distributed in the sea and in fresh water. Their body is completely enclosed in a bivalve carapace. Most ostracods are minute, several mm or less in length. Most ostracods are bottom dwelling, but there are a few pelagic species.
Ostracods can be carnivores, herbivores, scavengers, and filter feeders.
The bivalve Crustaceans in our area are poorly known. Papers in 1930 and 1952, reported thirty-five species, mainly from near Nanaimo, and seven species from Puget Sound.