Class of Crustacea - Copepoda
Copepoda is a huge class of small (1-5mm) crustaceans occupying both marine and freshwater environments. Copepods form the several abundant and conspicuous members of planktonic collection. Many are parasitic. Most copepods are brightly colored and some of the species are also bioluminescent. The body is cylindrical and tapering antero-posteriorly. The trunk is categorized into thorax and abdomen. The first and sometimes the second thoracic segment is fused along with the head. A median eye is present. The first pair of antennae are large and uniramous. The first pair of thoracic appendages is maxillipeds used for feeding. Abdomen has 5 segments and lacks appendages. Last abdominal segment has a pair of caudal rami. Planktonic copepods are either saprophytic feeders, or they may feed on phytoplankton or detritus. Few are carnivores. Nauplius larval stage seen.