| Echinothrix diadema | |
|---|---|
 | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | Echinoidea |
| Order: | Diadematoida |
| Family: | Diadematidae |
| Genus: | Echinothrix |
| Species: | E. diadema |
| Binomial name | |
| Echinothrix diadema | |
The diadema urchin or blue-black urchin (Echinothrix diadema) is a species of tropical sea urchin, member of the Diadematidae family.
Echinothrix diadema is a long spined urchin. With its spines, the typical diameter is 10–20 cm (3.9–7.9 in). [2] The internal organs are enclosed in the test, covered by a thin dermis and epidermis. [3] It is generally black or blue-black in colour, and always dark (the spines show a blue sheen in the light). The spines are closed at the tip; the anal sac is small and dark.
It differs from Echinothrix calamaris in that the spines are not banded, except in juveniles, and that its anal sac is small and hardly visible, and the spines show a blue sheen (whereas dark morphs of E. calamaris show a greenish tinge). Another similar species is Diadema setosum , which has longer spines and smaller test, the distinguishing feature being an orange ring around anal sac.
The grazing preferences of Echinothrix diadema in Fiji were found to correlate with its preferred algae/seagrass species, Codium geppiorum . [4] The grazing activity contributes to echinoid bioerosion. [5]
This species can be found throughout all the Indo-Pacific coral reefs, from the Red Sea to Hawaii. It is a shallow waters species, living between the surface and 10m deep, but can eventually be found down to 70m.
It is active at night, hiding in crevices, burrows, and under rocks during the day. Females generally choose low-lying locations, presumably so the tiny larvae can have better protection from predators. [6]
It hosts commensal species like the shrimp Stegopontonia commensalis . Saron marmoratus stays close for protection, like many fish of the families Apogonidae (cardinalfish) and Centriscidae (razorfish and relatives).
Bioerosion describes the breakdown of hard ocean substrates – and less often terrestrial substrates – by living organisms. Marine bioerosion can be caused by mollusks, polychaete worms, phoronids, sponges, crustaceans, echinoids, and fish; it can occur on coastlines, on coral reefs, and on ships; its mechanisms include biotic boring, drilling, rasping, and scraping. On dry land, bioerosion is typically performed by pioneer plants or plant-like organisms such as lichen, and mostly chemical or mechanical in nature.
The Diadematidae are a family of sea urchins. Their tests are either rigid or flexible and their spines are long and hollow.
Echinothrix is a genus of sea urchins which was first described in 1853 by Wilhelm Peters, a German naturalist and explorer.
Echinothrix calamaris, known commonly as the banded sea urchin or double spined urchin among other vernacular names, is a species of sea urchin in the family Diadematidae.
Diadema is a genus of sea urchins of the family Diadematidae.
Diadema antillarum, also known as the lime urchin, black sea urchin, or the long-spined sea urchin, is a species of sea urchin in the family Diadematidae.
Diadema setosum is a species of long-spined sea urchin belonging to the family Diadematidae. It is a typical sea urchin, with extremely long, hollow spines that are mildly venomous. D. setosum differs from other Diadema with five, characteristic white dots that can be found on its body. The species can be found throughout the Indo-Pacific region, from Australia and Africa to Japan and the Red Sea. Despite being capable of causing painful stings when stepped upon, the urchin is only slightly venomous and does not pose a serious threat to humans.
Aeoliscus strigatus, also known as the razorfish, jointed razorfish or coral shrimpfish, is a member of the family Centriscidae of the order Syngnathiformes. This unique fish adopts a head-down tail-up position as an adaptation for hiding among sea urchin spines. The razorfish is found in coastal waters in the Indo-West Pacific. Its natural habitat includes beds of sea grass and coral reefs, where sea urchins are found.
Astropyga radiata, the red urchin, fire urchin, false fire urchin or blue-spotted urchin, is a species of sea urchin in the family Diadematidae. It is a large species with long spines and is found in the tropical Indo-Pacific region. It was first described in 1778 by the German naturalist Nathaniel Gottfried Leske.
Heterocentrotus mamillatus, commonly known as the slate pencil urchin, red slate pencil urchin, or red pencil urchin, is a species of tropical sea urchin from the Indo-Pacific region.
Echinometra mathaei, the burrowing urchin, is a species of sea urchin in the family Echinometridae. It occurs in shallow waters in the Indo-Pacific region. The type locality is Mauritius.
Lytechinus williamsi, the jewel urchin, is a sea urchin in the family Toxopneustidae. It occurs on shallow reefs off the coasts of Panama, Belize, the Florida Keys and Jamaica.
Echinometra lucunter, the rock boring urchin, is a species of sea urchin in the family Echinometridae. It is found in very shallow parts of the western Atlantic Ocean and the Caribbean Sea.
Echinometra viridis, the reef urchin, is a species of sea urchin in the family Echinometridae. It is found on reefs in very shallow parts of the western Atlantic Ocean and the Caribbean Sea.
Diadema paucispinum, the long-spined sea urchin, is a species of sea urchin in the family Diadematidae. It is found in the western Indo-Pacific Ocean and in Hawaii and other east Pacific islands.
Diadema mexicanum is a species of long-spined sea urchin belonging to the family Diadematidae. It is native to the Pacific coast of Mexico, Costa Rica, El Salvador, Nicaragua and Panama.
Diadema savignyi is a species of long-spined sea urchin belonging to the family Diadematidae. Common names include long-spined sea urchin, black longspine urchin and the banded diadem. It is native to the east coast of Africa, the Red Sea, the Indian Ocean and western Pacific Ocean. It was first described in 1829 by the French naturalist Jean Victoire Audouin. The specific epithet honours the French zoologist Marie Jules César Savigny who described many new marine species from the Mediterranean Sea and Red Sea. The type locality is Mauritius.
Paracorynactis is a genus of corallimorphs from the western Indo-West Pacific. They are specialized predators of echinoderms, and are notable for preying on the destructive crown-of-thorns starfish among others. The genus is monotypic with the single species, Paracorynactis hoplites.
Stomopneustes variolaris, the black sea urchin or long-spined sea urchin, is a species of sea urchin, the only one in its genus Stomopneustes and only species still alive in its family Stomopneustidae. It is found throughout the tropical Indo-Pacific, with a patchy distribution.
Echinometra oblonga, also called the oblong urchin or 'ina 'ele 'ele in Hawaiian, is a very common rock boring urchin on shallow rocky shores of the tropical Indo-Pacific and Southern Africa.
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