Description
Diadema setosum, commonly called the diadem urchin or long-spined sea urchin, is a species of long-spined sea urchin known for its distinct five white dots and extremely long, hollow, mildly venomous spines. It's a typical sea urchin, with a round, hard shell (test) and numerous spines. Diadema setosum is primarily found in the Indo-Pacific region, including areas from Australia and Africa to Japan and the Red Sea.
Key Features:
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Spines: Long, hollow, and sharp spines that can cause painful stings, though only slightly venomous.
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Test: A round, hard shell made of fused plates.
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Color: Black or dark brown, with five distinctive white spots on its body.
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Habitat: Shallow tropical reefs in the Indo-Pacific, from Australia to Japan and the Red Sea.
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Behavior: Primarily a grazer, active at night, and vulnerable to predation from fish.
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Size: Maximum test diameter of 90 mm.
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Symbiotic relationships: Can host the urchin shrimp Stegopontonia commensalis.
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Diet: Algae.
Distinguishing Features:
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Diadema setosum can be distinguished from its sister species, D. savignyi, by the presence of white spots on its test, while D. savignyi has blue markings.
