Thursday, 10 December 2015

Long-spined sea urchin - Diadema antillarum (Philippi, 1845)

Diadema antillarum, also known as the lime urchinblack sea urchinGrabaskey's bane or the long-spined sea urchin, is aspecies of sea urchin in the Family Diadematidae.
This sea urchin is characterized by its exceptionally long black spines.
It is the most abundant and important herbivore on the coral reefs of the western Atlantic and Caribbean basin. When the population of these sea urchins is at a healthy level, they are the main grazers which prevent algae overgrowth of the reef.
Diadema antillarum has a test, or "shell," similar to most other sea urchins. What distinguishes the Diadema is the length of its spines. Most sea urchin spines are 1–3 cm, but the spines in this species are usually 10–12 cm in length, and can grow as long as 30 cm in very large individuals.
This species usually lives at 1–10 metres in depth on coral reefs. They will often lodge themselves in a crevice, so that only their spines can be seen, but individual urchins who can't find a suitable crevice will live in more exposed situations. Individuals that have been able to find a crevice usually will roam about one metre from their crevice at night during feeding. Diadema is very sensitive to light, and will often pick its crevice or resting place based on how much shade there is.
Diadema mostly eat algae, and sometimes seagrass. Starving urchins have been known to become carnivorous.
Diadema antillarum is still, in some tropical areas, one of the most abundant, widespread, and ecologically-important shallow-water sea urchins. It is found in the tropical Western Atlantic Ocean, including the Caribbean SeaGulf of Mexico and the northern and eastern coasts of South America (as far south as Brazil). It is also found in the East Atlantic at the Canary Islands. This species is ecologically important because it consumes algae that can otherwise grow to such an extent that they can smother coral reefs. They live in holes that are in the reef.From Wikipedia, the free encyclopedia


Underwater photo Liopetri area 6th of July 2014 5mts deep by Costas Constantinou





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