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Starfish

Common Brittlestar

Ophiothrix fragilis

Ophiothrix fragilis (Abildgaard in O.F. Müller, 1789) · Ophiotrichidae WoRMS 125131

Reference photos

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A spiny, five-sided disk up to 2 cm across, trailing five long slender arms about five times the disk diameter, each segment carrying seven serrated spines. The arms are fragile, often broken, and can be shed to escape a predator, then regrown. Colour is very varied, commonly brown or grey but also purple, red, orange, yellow or white, plain or banded. Shelters in crevices and under boulders on the shore, and offshore forms dense beds of up to 2000 animals per square metre.

Depth

Lower shore down to about 85 m, with records to 150 m and as deep as 350 m

Size

Disk up to 2 cm across, with five arms about five times the disk diameter; 11-20 cm overall

Habitat

Bedrock, boulders and coarse sediment from the lower shore to offshore, most abundant on tideswept ground; in crevices and under boulders on the shore

Behaviour

Gregarious passive suspension feeder, arms held up into the current; gathers in dense beds of up to 2000 per square metre and shelters in crevices by day

Diet

I eat

  • Phytoplankton, diatoms and fine detritus taken from the water
  • Suspended particles strained from the current with the arms held up into the water
  • Material off the seabed surface when the current slackens, and dead animals scavenged now and then

Eats me

  • Bottom-feeding fish, including ballan and cuckoo wrasse, dragonets, cod and plaice
  • Crabs, especially swimming crabs such as the velvet crab
  • Predatory starfish: the common starfish and the spiny starfish, whose chemicals alone make it flee, and Luidia ciliaris

Where you'd find it

Found around most of Britain and Ireland, though less often in the waters west of Ireland.

ChannelCeltic SeaNorth SeaIrish SeaW of IrelandW of Scotland
Often seenNow and thenWhere PEBL filmsBased on marine survey records (OBIS). Blank seas can mean nobody has looked there, not that the animal is absent.

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.

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