(Montagu, 1808)
Description:
Body elongate, laterally flattened. Coxal plate 1 prolonged, anterior angle rounded, plates 2 to 5 rounded; epimeral plates 1 to 3 rounded. Head with rounded lateral lobes, eyes small, oval. Antenna 1 and 2 about equal in male, in female antenna 1 may be a little longer than antenna 2; antenna 1 peduncle article 3 almost half the length of article 2, flagellum slender, up to about 35-articulate; antenna 2 peduncle robust especially in male, flagellum short, up to about 15-articulate. Gnathopod 1 moderately setose, basis with a moderately large anterodistal lobe, propodus oval, palm oblique, weakly convex, delimited by a small spine, dactylus longer than the palm. Female gnathopod 2 slightly larger than gnathopod 1, carpal lobe slender, palm weakly concave. Male gnathopod 2 much larger than gnathopod 1, basis with a small anterodistal lobe, carpus with a slender posterior lobe, propodus broadly oval, inner surface very strongly setose, palm concave. Pereiopods 5 to 7 basis only slightly expanded, propodus weakly expanded distally. Uropod 3 peduncle inner distal margin with about six small spines, outer ramus with two strong hooks and a small group of long dorsal setae, inner ramus with long apical setae and three or four small spines. Telson rounded, apex convex between small lateral cusps.
Size:
Up to about 20 mm.
Colour:
Variable, red to green with dark markings, often with white spots on the pereion.
Habitat:
A very common intertidal or shallow subtidal amphipod; locally abundant; lives in tubes attached to algae or beneath stones.
Distribution:
North Atlantic, American and European coasts; North Pacific; Arctic Ocean. European coasts from northern Norway to north-west France and the southern Baltic. Very widespread and frequently recorded.