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Long-spined black sea urchin - Diadema setosum - Long spines

Body diameter 8-10cm. It has very long primary spines, up to 30cm long, with many shorter spines in between. The spines on the underside are much shorter. The urchin can rapidly point its long spines against any potential threat (which is quite a scary thing to observe). The spines may be all black, banded black-and-white or even all white.There is bulbous sac in the middle of the upperside. This is the anal cone through which wastes are discharged. There is an orange ring around this anal cone, sometimes the ring is pale. There are five bright white spots on the black body, with small bright blue dots forming V-shape lines from the white spots. The underside may be pale, dark or maroon or pink.

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Long-spined black sea urchin - Diadema setosum - Long spines

by Dieter

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Uploaded on July 17, 2022

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