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Urchin

Purple sea urchin

Paracentrotus lividus

Paracentrotus lividus (Lamarck, 1816) · Parechinidae WoRMS 124316

Reference photos

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A rock pool urchin with a greenish, flattened test up to 7 cm across and long, sharp spines of dark purple to dark green. It bores into soft rock with its spines and teeth and sits in the burrow, sheltered from the waves and from drying out at low tide. In Britain and Ireland it belongs to the south and west, common on the west coast of Ireland and scarce elsewhere.

Depth

Lower-shore rock pools and the shallow sublittoral, mostly down to about 3 m and recorded to about 30 m

Size

Round, flattened test up to 7 cm in diameter

Habitat

Lower-shore rock pools and crevices on rocky shores, boring into soft rock, also on stony ground, maerl gravel and in Zostera seagrass beds

Behaviour

Bores a hole in soft rock with its spines and teeth and shelters in it, enlarging it as it grows; many together can honeycomb the rock

Diet

I eat

  • Seaweeds and other macroalgae, grazed hard enough to strip a shore back to bare rock and encrusting corallines
  • Dulse (Palmaria palmata), a red seaweed on which it has been successfully reared in culture in western Ireland
  • Seagrass, including shallow beds it can overgraze where it is abundant

Where you'd find it

Mostly seen in the waters west of Ireland, and only here and there elsewhere.

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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