Description: This starfish is large and has five very spiny arms. Each arm bears three longitudinal rows of spike-like spines surrounded by large cushions of pedicellariae. Smaller spines may be scattered between these rows. The spines are white and usually purple-tipped and the animal varies in colour from dirty brown to greenish-grey with purple tips to the arms. Up to 35cm or more in diameter.

Habitat: This species may be found in a very wide range of habitats from sheltered muddy sites to fully exposed rockfaces. Specimens from sheltered sites are usually larger than those from exposed sites.

Distribution: Apparently confined to the southwest and west coasts of the British Isles, also north to Scandinavia.

Similar Species: Small individuals might be mistaken for Leptasterias muelleri.

Key Identification Features:

• Large spines forming three main rows along each arm.
• Spines surrounded by a wreath of pedicellariae.
• Spines usually white with purple tips.

Distribution Map from NBN: Marthasterias glacialis at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Marthasterias glacialis at iNaturalist World Species Observations database.