The Tropical Spined Sea Urchin (Diadema savignyi) has a worldwide distribution and belongs to the family Diadematidae. It has been recorded from the waters of East Africa, Red Sea, Japan, Philippines, Solomon Islands, Tahiti, Fiji, Madagascar and Australia. In Australia it is known to occur from the Abrolhos Islands in Western Australia around the north to Sydney Harbour in New South Wales. This species is generally found in shallow warm waters of tropical coral reefs and is known to occur from depths of 0 to 70 metres.
This tropical sea urchin is known to feed on algae and food particles suspended in the water column that get caught in the long spines. This species looks very similar in appearance to the Diadem Needle Spined Sea Urchin (Diadema setosum. This species can be recognised by its black anal cone and radiating electric blue lines over its body.
The Tropical Spined Sea Urchin (Diadema savignyi) is known to grow to a maximum width of approximately 23cm.