Another member of the “cleaner crew” sea urchins are a phenomenal addition to any fish tank and work hard at keeping it at an ideal Ph for the rest of the system.
Diadema antillarum is a regular (round) urchin, and displays the pentamerism of echinoderms. Mature individuals of D. antillarum can reach up to 500 mm in diameter. Diadema antillarum has thin spines that range from 300-400 mm in length and can be up to four times the diameter of the test (skeleton formed inside the body). The spines are thin, hollow, and break easily.
The test and spines of a mature adult are typically black, but lighter colored spines may be intermixed, and in rare cases the urchin will be almost entirely white. The spines of juveniles are always banded with black and white. At the base of the urchin are branched tentacles called tube feet, which help in gathering food, respiration, locomotion, and mucous production.
Diadema antillarum is found in the shallow waters of the Atlantic Ocean, in the Bahamas, and the Western Atlantic from eastern Florida to Brazil. In the Eastern Atlantic D. antillarum is found in Madeira, the Gulf of Guinea, and the Canary, Cape Verde, and Annabon islands.