(phylum Arthropoda, subphylum Crustacea)
Class of crustaceans, first described in 1943, known from only three species in one genus, Derocheilocharis, and related to the copepods and barnacles. Mystacocarids are tiny filter feeders, 0.5 mm or less in length, and are adapted for life between intertidal sand grains. Although the elongate, cylindrical body is divided as that of the copepods, transverse constriction divides the head, and the thoracic segment bearing the maxillipeds is only incompletely fused with the head. Four of the five thoracic segments bear uniramous appendages, each reduced to a single, simple lamella. Both pairs of antennae are well developed, and the feeding appendages are setose, and longer than those of the copepods. Only a nauplius eye is present.
Subjects: Zoology and Animal Sciences.