Barnacles and Copepods

Barnacles and copepods were both formerly members of the class Hexanauplia, and remain grouped together on this site. While they may resemble limpet snails, barnacles are actually a type of crustacean, more closely related to crabs and shrimp. Many are sessile, attached directly to the substrate, whilst some are attached via stalks. They feed on suspended particles by extending their feathery, heavily-modified legs through the central aperture. Copepods are generally free-swimming or parasitic organisms that resemble some isopods and amphipods. They are usually near-microscopic.