Calman, 1904
Members of the eumalacostracan Superorder Eucarida are crustaceans with a well developed carapace that is characteristically fused to all thoracomeres to form a cephalothorax. The gills are located on the thorax and partially or completely covered by the carapace. The eyes are stalked and compound. The mandibles are without a licinia mobilis. There are one, three, or no maxillipeds; the telson has no caudal rami. Larval development is typically metamorphic (see also below). The Eucarida comprise three orders, of which one (*) is absent from the North Sea:
¥ÊOrder Euphausiacea (pelagic, known also as krill)
¥ Order Amphionidacea* (pelagic)
¥ Order Decapoda (pelagic and benthic, a very diverse group that contains crustaceans as shrimps, prawns, lobsters, and crabs)
Larval development
Naupliar stages occur only in the development of the Order Euphausiacea, and in the Superfamily Penaeoidea and Superfamily Sergestoidea, both belonging to the Order Decapoda. In all other Eucarida the naupliar phase is passed within the egg membrane and larvae hatch as zoea.
The eucarid nauplii are distinguished from nauplii of other crustacean superorders by the lack of masticatory spines at the bases of the antenna or the mandible. It is not possible to separate systematically the naupliar stages from the above mentioned Euphausiacea, Penaeoidea and Sergestoidea.
Zoeal stages occur in all Eucarida. (See also Crustacean larval stages).
[Description after McLaughlin, 1980; Brusca and Brusca, 1990]