Rock Sea Urchin

(Paracentrotus lividus)




Facts about this animal

The Rock Sea Urchin is a regular sea urchin what means that its test shows a radial symmetry. The colour is dark violet, olive-green, brown or even black. The test can be 5-7 cm wide and the spines up to 3 cm long. The spines are thick and smooth. There are 5-6 meridian rows of paired pores on the ambulacral plates. As in all sea urchins there is a complex jaw mechanism with five teeth – called Aristotle’s lantern – within the ventral mouth.

By day it often rests in small cavities bore itself with its spines (or teeth?) or covers itself with shell debris or algae by means of its tube feet. By night it forages on red algae sometimes also blue-green algae, seagrass and sponges. Overgrazing rocks may cause visible clearings.

Known enemies are spiny lobsters, sea stars and fishes.

The sexes are separate and fertilization is external. Each animal has 5 edible gonads which develop during summer and autumn, mature in winter to spawn in spring and early summer. The larvae, called echinopluteus, are pelagic and show a bilateral symmetry. When the larva settles it metamorphoses to a small sea urchin.

Did you know?
that the roe of the Rock Sea Urchin is edible and is commercially important in the Medierranean? that the catch of the Rock Sea Urchin is therefore regulated in France with a summery close season and a permission is needed for fishermen? that about half of the species of sea urchins are so-called irregular because they are not round but heart-shaped and flat with short spines to dig in sandy ground, and are named “sand dollars”?


Name (Scientific) Paracentrotus lividus
Name (English) Rock Sea Urchin
Name (French) Oursin violet, Oursin-pierre, Châtaigne de mer
Name (German) Steinseeigel
Name (Spanish) Erizo de mar común, Castan de mar, Erizo marron
Local names Italian: Riccio femina, Riccio viola
Portuguese: Ourico do mar, castanho
CITES Status Not listed
CMS Status Not listed




Range Mediterranean and north-eastern Atlantic Ocean from the west coast of the British Isles to Morocco, the Azores and Canary Islands.
Habitat The Rock Sea Urchin dwells rock pools or lime rocks, seagrass meadows, corals or sandy bottom in shallow water or rarely down to 30-80 m depth.
Wild population Very common, but overfishing can harm local populations.
Zoo population 14 reported to ISIS (2008)

In the Zoo

Why do zoos keep this animal

The Rock Sea Urchin is commercially important seafood unknown to most people in this respect. Since its spines do not harm it can also be used in touch pools.