Echinus acutus is a sea urchin that has a diameter of up to 15 cm. Its
test is conical and its colour is reddish to brown-red, sometimes green, with vertical white
stripes on the ambulacral plates. Spines are scarce, greenish or reddish at their base and white at
their tips. There are two types of spines : primary ones are long and tapering, secondary ones are
shorter and thinner. There are no spines around the mouth but instead many pedicellariae. The white
sea urchin feeds on algae and small organisms such as crustaceans.
Echinus acutus is found on coarse sustrata mixing stones, gravel and muddy sand from 20 to more than 1000 m deep in the Atlantic Ocean, the English Channel, the North Sea and The Mediterranean Sea.
(source : European Register of Marine Species)
Test : Rigid skeleton of sea urchins.
Ambulacral plates : Test plates pierced by numerous holes through which tube-feet can extend.
Pedicellariae : Minute jawed elements of sea urchins and starfish used to clean body surface and as defensive means.
Top Photo :
© Mat Vestjens. Published with author's kind permission:
Echinus acutus, Lysefjord, Rogaland, South-Western Norway. Depth 18 meters.
Text : Anne Bay-Nouailhat © 2008-2014.
Translation : Anne Bay-Nouailhat © 2008-2014.