Rostrum straight, unarmed, normally extending little beyond distal end of basal segment of antennular peduncle, apex acutely pointed.
Carapace with anterior projections which partly cover the eyes in dorsal view, the projections bearing two lateral spines plus small dorsal lobe.
Stylocerite narrow, acutely pointed, 0.66-0.75 x length of scaphocerite, slightly longer in large specimen.
Scaphocerite equal in length to antennular peduncle, apical spine stout, exceeding lamellar portion. Third maxilliped about equal in length to scaphocerite; epipod and exopod present.
Mandible with incisor and molar process, and two-segmented palp.
Pereiopods 1-3 with epipods, setobranch on pereiopod 4. Pereiopod 1 with reduced exopod. First pereiopods larger than second pair, often asymmetrical in male.
Carpus of pereiopod 2 with five segments. Pleonite 6 with articulated process at base of uropods.
Telson with two pairs of lateral spines.
Length up to 20 mm.
Variable. Often green, blue or red-brown, frequently with a longitudinal white dorso-median stripe extending the full length of the animal. May also be almost transparent, speckled with red chromatophores.
Down to about 65 metres. Hyperbenthic species, may swim up at night, but mostly confined to the nepheloid layer.
Occasionally in rock-pools. May occur under large stones especially where the substrate is gravelly. Often occur in groups of adults and juveniles.
Ovigerous females occur from May to August-September.
Distribution in the North Sea:
All North Sea.
Ranges from S and W Norway and W coast of Sweden southwards to the Cape Verde Islands and into the Mediterranean and Black Sea.