VIMS Zooplankton Ecology - BATS Ostracoda

Ostracods are a class under the subphylum Crustacea of the phylum Arthropoda. The majority of the species are benthic and have heavily calcified carapaces. Palaeontologists can identify the species of many fossilized shells and use this information, along with knowledge of the environmental preferences by the species, to determine past climatic conditions. The bivalve carapace of planktonic ostracods, which includes most of the family of Halocyprididae and a few species of Cypridinididae, have little, if any, calcification, an adaptation to free-living in the water column. Adult sizes range from 0.5 to 30 mm, but most are between 0.8 and 4 mm. Although small, planktonic ostracods have high numerical abundance, often outnumbered only by copepods. Ostracods are omnivorous, eating phytoplankton, zooplankton, and detritus. Thus, given their numbers, they may play an important role in recycling material in the ocean. Most ostracods go through six juvenile stages before becoming an adult. Juvenile stages can be determined by the number of hook setae on the caudal furca. Both seasonal and ontogenetic vertical migrations occur in many species.