(M. Sars, 1846)
Northern Starfish
Description
Body with a very small disc and five tapering arms; R/r: 4 to 7; up to 200 mm in diameter, but usually not exceeding 100 mm. Coloured pink or pale violet to green, grading to off-white at the ends of the arms. The body wall is strengthened by a reticulate pattern of plates. The body wall of this species is tougher than in Asterias rubens, with less space between the plates.
Dorsal side
On the dorsal side, the knob-shaped spines are generally only indistinctly arranged in longitudinal series (mostly in juveniles; in larger specimens, the spines are scattered). These spines are often surrounded by bunches of crossed pedicellariae at the base. The papulae are mostly singly placed in the soft areas.
Oral side
The adambulacral spines are as a rule positioned in a single series for some distance on the proximal part of the arms. Farther out, they are alternating one and two, or sometimes only apparently so, alternatingly bending inwards and outwards. The ventro-lateral spines are single and are furnished with straight pedicellariae near their tips (L. muelleri spines).
Habitat
This species prefers hard substrata and is found from the low tide mark down to depths of about 800 m.
Distribution
This is a northern species, distributed from the North Sea, the west coast of the Shetland Islands up to Spitzbergen, Greenland and North America.