Rostrum straight, little over half the length of antennular peduncle; three or four (rarely five or six) dorsal teeth, tip bi- or tri-dentate, rarely a single point.
Carapace with antennal spine.
Stylocerite acutely pointed, 0.66 x length of antennular peduncle.
Scaphocerite outer margin straight or very slightly concave, apical spine only very slightly shorter than lamellar portion. Third maxilliped extends to just beyond tip of scaphocerite; exopod and small epipod present.
Mandible with molar and incisor process, but without palp.
Pereiopods 1 and 2 with epipods, setobranch on pereiopod 3. Ventro-posterior border of merus of pereiopod 3 with seven to fourteen spines in male and two to five spines in female. Carpus of pereiopod 2 with six segments.
Telson with two to seven pairs of lateral spines, nominally with four pairs.
Length up to 22 mm, but usually below 20 mm.
Variable. Often semi-transparent with black, red, orange and yellow chromatophores scattered over body and limbs, ventral area of pleon often a darker red. Occasionally whole animal may be dark brownish-green, with redbrown stripes on body and limbs.
Has been taken down to 70 metres off British coasts and down to 130 metres elsewhere. Frequently amongst algae or in pools at ELWS, sometimes occurring with Eualus occultus. It is not certain whether this species never swims up into the water column. Ovigerous females occur from March to August-September.
Distribution in the North Sea:
Southwestern North Sea, British east coast, possibly all North Sea.
Ranges from W Norway southwards into the Mediterranean, Cape Verde Islands and Gulf of Guinea.