Achelia echinata

Hodge, 1864

Body thick and massive, somewhat depressed, 2nd trunk segment well separated from the cephalon as well as from the following one; the last two segments coalesced. The lateral corners of the frontal part drawn out to conical prominences projected forward. Lateral processes thick, almost contiguous, each furnished at the end at the dorsal side, with two equally developed spiniform processes terminating in a stiff bristle. Cephalon massive, with an indistinct neck and a square frontal part. Ocular tubercle somewhat anteriorly directed, almost cylindrical, the point blunted, with a short medial prominence; the eyes placed near the top. Proboscis more than half as long as the rest of the body. Chelifores about half the length of the proboscis, the scape passing into a bifurcated projection at the dorsal tip, furnished with two spines; the terminal segment globular in form. Palps with eight segments, rather slender, 2nd segment longer than the 4th, the latter shorter than the terminal part.
Ovigerous legs present in both sexes, with 7-10 segments, relatively short, without a distinct terminal claw and with a very small number of serrated marginal spines.
Ambulatory legs hardly twice as long as the body, powerfully built and partly beset with spines; the two first coxal segments in male, each with two spiniform processes arranged in pairs; the outer corner of the femur with a conical projection; propodus almost uniform in breadth, strongly bent, and at the base furnished on the inner margin with three strong spines; terminal claw about half the length of the propodus; auxiliary claws well developed and half the length of the terminal claw.
Colour yellowish. Length of the body up to 2 mm; the extent between the points of the ambulatory legs reaching 7 mm.

Sublittoral, often on Dynamena pumila and Flustra foliacea , feeding on the latter bryozoan by thrusting its proboscis into the operculum when it opens.

This species is of wide occurrence and may be part of a large species-complex in the Northern Hemisphere, spreading from the Arctic almost to the Equator.