Starfish
Spiny Starfish
Marthasterias glacialis
Marthasterias glacialis (Linnaeus, 1758) · Asteriidae WoRMS 123803
Reference photos
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A big, spiny starfish: five narrow tapering arms, each with three lines of white, purple-tipped spines set in cushions of pedicellariae. Dirty brown to pale greyish green, up to 70 cm across but usually 25-30 cm.
Depth
From extreme low water down to about 200 m
Size
Up to 70 cm across, commonly 25-30 cm
Habitat
From the intertidal into the subtidal on rocky coasts, in a variety of habitats from sheltered muddy sites to wave exposed rock faces
Behaviour
A slow-moving predator that finds prey by chemoreception and chance encounter, taking a wide range of prey
Diet
I eat
- Mussels above all: the most-taken prey item at every depth on shallow rocky reefs, and preferred over urchins and snails in feeding trials
- Sea snails: prosobranch gastropods, the next most frequent prey after mussels
- Sea urchins and barnacles; in the Mediterranean it can hold down densities of the purple sea urchin
Eats me
- Other starfish: the seven-armed starfish and the sunstars are recorded predators, and the common starfish also takes it as prey
- Crabs, including the edible crab and the great spider crab, recorded as predators at the northern end of its range
- Atlantic cod: sea stars of this genus are among its recorded food items in Scottish waters
Where you'd find it
Found around most of Britain and Ireland, though less often in the North Sea.
Sources
Open-access references behind this page. Every statement on this page was read out of one of them; anything that could not be traced to a source was taken off the page rather than left standing. Each link was checked on the date shown, and confirmed then to be about this species.
Mytilus edulis - BIOTIC (Biological Traits Information Catalogue) species record
BIOTIC, Marine Life Information Network / Marine Biological Association of the UK
WebCC BY-NC-SA 4.0link checked 2026-08-30
Scientia Marina (CSIC) (2012)
PaperCC BY 4.0link checked 2026-08-30
Common starfish (Asterias rubens)
Marine Life Information Network, Marine Biological Association of the UK
MarLINlink checked 2026-08-30
Spiny starfish (Marthasterias glacialis)
Marine Life Information Network, Marine Biological Association of the UK
MarLINlink checked 2026-08-30
Natural Resources Wales (2020)
ID guidelink checked 2026-08-30
Marthasterias glacialis (Linnaeus, 1758)
World Register of Marine Species (WoRMS Editorial Board)
TaxonomyCC BY 4.0link checked 2026-08-30
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