Body with a central disc of up to 35 mm in diameter and 5 arms of about four times that length; coloured reddish or darker, often somewhat mottled.
The scales of the disc are rather coarse, the primary plates are generally distinct. The radial shields are about half the length of the disc radius and are separated, or contiguous at their broadest part. The arm combs consist of short, rather broad papillae, ca. 9-12 in the outer comb (O. sarsi disc).
The innermost dorsal arm plates (generally 4) are usually rectangular or triangular. The free dorsal arm plates in the proximal part of the arm are 4-5 times as broad as long, with a straight or concave outer edge and are contiguous throughout their whole breadth (O. sarsi arm dorsal). The ventral arm plates are twice as broad as long, with a convex outer edge. There are 3 arm spines per segment. The proximal tube foot pores with 3-4 tentacle scales, farther out only 2 or 1 (O. sarsi arm ventral).
The mouth shields are conspicuous shorter than the distance from their outer edge to the edge of the disc. There is a single vertical row of teeth on top of the jaw, and 4-6 pointed mouth papillae on each side of the jaw (O. sarsi mouth).
???, from about 10-3000 m.
In the North Sea this species is found as far south as Helgoland. The species is circumpolar. At the Atlantic east coast it goes down as far as south Ireland, while at the west coast it occurs to 35 degrees. In the Pacific it is found as far south as Japan and California.