Length: 7-30mm. Head with one pair, anteriorly pointing spines; body with many spines of varying size and position, mature males bearing the fewest + smallest spines; in some individuals so much reduced to be hardly noticeable. Typical dorsal spination pattern: one pair posterior on pereonite 1; 2-3 pairs spaced along pereonite 2; numerous pairs dorsal + lateral pereonites 3-4-5; 1 pair pereonites 6+7. Antenna 1 longer than cephalon plus pereonite 2, peduncle stout and densely setose. Antenna 2 shorter than two basal articles of antenna 1, flagellum with swimming setae. Gnathopod 1 propodus and dactylus grasping margin slightly serrate. Gnathopod 2 propodus large, more than twice as long as broad, palm with proximal grasping spine, small distal poison spine, and large triangular distal projection. Dactylus thickened proximally, tapering distally. Basis attached posteriorly on pereonite 2 and bearing antero-lateral ridge. Gills large, round or oval. Pereopods 5, 6 and 7 increasing in length, propodus with proximal paired grasping spines. Female differs in no lengthening of anterior pereonites; antenna 1 not greatly enlarged or setose; antenna 2 longer than antenna 1 peduncle; gnathopod 2 attached anteriorly.
California, Washington, British Columbia, Alaska (including Dutch Harbor)
It is under debate whether Metacaprella represents a true genus. For this reason, Metacaprella spp. have been included under Caprella. See: Caprella kennerlyi
Caprellid, “Ghost” or “Skeleton” shrimps, so called for their skeletal appearance. Amphipod crustaceans, easily distinguished by the elongate stick-like body form and reduction of the abdominal appendages. Head is generally fused with pereonite 1. Pereopods on first 2 segments (pereonites) are most flexible and called gnathopods; gnathopods 2 being the largest, used in defense, feeding and substrate attachment. In many species pereopods 3 and 4 may also be reduced or absent. Gills on pereonites 3 + 4, rarely on pereonite 2. Pereopods 5 - 7 much smaller than 1 + 2, used for clinging to the substratum. In females, brood plates (öostegites) develop on pereonites 3 + 4. Much remains to be learnt about their biology, ecology and in many cases changing distributions.
From open shores, intertidal and subtidal, on many substrates (hydroids, bryozoans, abalone shells, radioles of sabellid worm) and marine fouling communities. Plumularia lagenifera
Easily distinguished from Caprella anomala (previously grouped together as Metacaprella) by antenna 1. Distinguished from Caprella ferrea and Caprella alaskana by head spines rather than tubercles; body spination and peduncle of antenna 1.
National Museum of Natural History, Washington DC: (NMNH) 25950
