White, 1847
Body cylindrical. Head free, partially, or completely fused with the first pereion segment. The antroventral margin of the head is straight or concave with an almost square anteroventral corner. The first antenna is longer than or subaequal to the second antenna. The mouthparts are well developed.
The pereion has seven segments, without pleurae and sternal gills. Two (rarely three) pairs of simple sac-like branchial lobes, without accessory branchiae.
The first gnathopod is smaller than the second gnathopod; the first gnathopod sometimes, second gnathopod always subchelate.
Pereiopods 3 and 4 are absent; pereiopods 5-7 some or al prehensile. Pleon reduced, three segments. Pleopods more or less rudimentary in the male, almost always absent in female.
Larval development is epimorphic, there is no postlarval stage.
Ecology
Caprellids are usually benthic and live clinged to other organisms, such as filamentous algae, bryozoans, hydroids, and sponges, but also on buoys and pontoons. Occasionally they occur in the plankton when swept away by (tidal) currents.
Distribution in the North Sea
About ten species are known from our area. For example Caprella linearis (Linnaeus, 1767). Caprella linearis