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Urchin

Green sea urchin

Psammechinus miliaris

Psammechinus miliaris (P.L.S. Müller, 1771) · Parechinidae WoRMS 124319

Reference photos

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A small, almost round urchin, greenish with distinctive violet tips to its short, robust spines. Found on all British and Irish coasts, intertidally on rocky shores under stones, boulders and seaweed, and subtidally in seagrass beds and on mixed coarse bottoms of muddy sand and gravel, from the shore down to about 100 m.

Depth

0 to 100 m, from intertidal pools downwards; most commonly 16 to 70 m, or 0 to 10 m in Scottish sea lochs

Size

Up to 57 mm across the test, more typically about 35 mm

Habitat

Rocky shores under stones, boulders and seaweed, and subtidally in seagrass beds and on muddy sand and gravel

Behaviour

An omnivorous crawler, grazing algae and encrusting animals; occurs in dense, localised populations in sheltered sea lochs

Diet

I eat

  • Seaweed, probably mostly loose-lying brown algae such as sugar kelp, with softer green algae important when small
  • Encrusting animals living on the bottom: hydroids, bryozoans, barnacles and boring sponges
  • Small bivalves such as mussels and cockles, and worms

Eats me

  • Starfish and crabs
  • Fish, including the wolf fish (Anarhichas lupus)
  • Birds such as gulls and oystercatchers, taking urchins at low tide

Where you'd find it

Found around most of Britain and Ireland, though less often in the Celtic Sea and 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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