(O.F. Müller, 1776)
Body with a very small disc, and 5 slender and tapering arms with no distinct margin between upper and lower surface; R/r: 4.5; up to 200 mm in diameter. In large specimens, the arms may be very much swollen and broad. Colour varying from red to pink and yellow (H. sanguinolenta pink, H. sanguinolenta yellow).
The upper surface is irregular with scattered groups of small spines. The number of spines in these groups varies.
On the oral side, the spines on the adambulacral plates general form a single transverse series, diminishing gradually in size outwards. The plates outside the adambulacrals are generally small and not very regularly arranged in longitudinal or transversal sereis.
This species prefers hard substrata and is found from shallow water down to depths of 1000 m or more.
Circum Arctic distribution, from the British north coasts and the Scandinavian seas down to the Bay of Biscay and the Azores. Elsewhere found in Greenland, Iceland, Baltic, north-west Atlantic and the north Pacific.