Protozoea

one of the larval stages in the development of decapod Crustacea. The protozoean stage usually occurs in the egg; a free-floating protozoea is characteristic of a few primitive shrimp. The protozoea has a segmented thorax, an unsegmented abdomen, a cephalothoracic shell, and a pair of compound sessile eyes. After ecdysis, the protozoea passes into the next larval stage, the zoea.