Gracilechinus 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.
Gracilechinus 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.
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Source : World Register of Marine Species
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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.
Text : Anne Bay-Nouailhat © 2008 - 2022.
Photos : ©
Mat Vestjens. Published with his kind permission.
Websites and reference works : Consult bibliography
Bay-Nouailhat A., August 2008, Description of Gracilechinus acutus, [On line] https://european-marine-life.org/30/gracilechinus-acutus.php, consulted on 2022 September 25.
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