| Arbacia lixula Temporal range: | |
|---|---|
 | |
| Arbacia lixula from the Mediterranean | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | Echinoidea |
| Order: | Arbacioida |
| Family: | Arbaciidae |
| Genus: | Arbacia |
| Species: | A. lixula |
| Binomial name | |
| Arbacia lixula | |
Arbacia lixula, the black sea urchin, is a species of sea urchin from Europe.
It is a medium-sized sea urchin, characterized by its deep black color and its hemispherical shape. All of its spines are roughly the same size (no "secondary spines"), and worn erected (never dishevelled when in the water). The anus on the top is surrounded by four plates forming an anal valve. The oral face is nearly naked, the mouth being surrounded by soft, dark-greenish skin. [2]
This species can be confused with the purple sea urchin Paracentrotus lividus , but the latter is never really black (though often very dark), has more dishevelled spines of many lengths, covers itself with debris, has spines around the mouth and no anal valve, and does not live exposed on the cliffs.
This species can be found on the coast of the Mediterranean Sea and Macaronesian Islands (Azores, Madeira, Canary Islands), and less commonly, on the Atlantic coast of Western Africa and the Brazilian coast. It is found typically at shallow waters, at depths from 0 to 30 m, in rocky shores. It has a good resistance to hydrodynamism due to a good attachment strength to rocks.
This species feeds mainly on crustose red algae and small filamentous algae. In a marine reserve in the Mediterranean, its population increased by a factor over 10 between 1983 and 1992, from eight to 100 individuals per meter2. High seawater temperatures are thought to favour this species. When it was excluded from an area of the reserve, the density of filamentous algae increased. [3]
Sea urchins are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin are distributed on the seabeds of every ocean and inhabit every depth zone from the intertidal seashore down to 5,000 meters. The spherical, hard shells (tests) of sea urchins are round and covered in spines. Most urchin spines range in length from 3 to 10 cm, with outliers such as the black sea urchin possessing spines as long as 30 cm (12 in). Sea urchins move slowly, crawling with tube feet, and also propel themselves with their spines. Although algae are the primary diet, sea urchins also eat slow-moving (sessile) animals. Predators that eat sea urchins include a wide variety of fish, starfish, crabs, marine mammals, and humans.
The red sea urchin is a sea urchin found in the northeastern Pacific Ocean from Alaska to Baja California. It lives in shallow waters from the low-tide line to greater than 280 m (920 ft) deep, and is typically found on rocky shores sheltered from extreme wave action in areas where kelp is available.
The diadema urchin or blue-black urchin is a species of tropical sea urchin, member of the Diadematidae family.
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 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.
The orange-lined triggerfish is a demersal triggerfish. Although Balistapus is a monotypic genus, it is closely related to the genus Balistoides.
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.
Meoma ventricosa, known by the common names cake urchin and red heart urchin, is a large species of sea urchin which lives in shallow waters in the Caribbean. It may reach a diameter of twenty centimeters and is covered in reddish-brown spines. It has both pentagonal radial symmetry and bilateral symmetry, giving it a sand-dollar appearance; however, two of its five sections are merged more closely than the others.
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.
Bald sea urchin disease is a bacterial disease known to affect several species of sea urchins in the Mediterranean Sea, North Atlantic and along the California coastline. Research suggests two pathogens are responsible for the disease, Listonella anguillarum and Aeromonas salmonicida.
The Echinacea are a superorder of sea urchins. They are distinguished by the presence of a rigid test, with ten buccal plates around the mouth, and solid spines. Unlike some other sea urchins, they also possess gills. The group is a large one, with species found worldwide.
Tripneustes gratilla, the collector urchin, is a species of sea urchin. Collector urchins are found at depths of 2 to 30 metres in the waters of the Indo-Pacific, Hawaii, the Red Sea, and The Bahamas. They can reach 10 to 15 centimetres in size.
Toxopneustes pileolus, commonly known as the flower urchin, is a widespread and commonly encountered species of sea urchin from the Indo-West Pacific. It is considered highly dangerous, as it is capable of delivering extremely painful and medically significant stings when touched. It inhabits coral reefs, seagrass beds, and rocky or sandy environments at depths of up to 90 m (295 ft). It feeds on algae, bryozoans, and organic detritus.
Paracentrotus lividus is a species of sea urchin in the family Parechinidae commonly known as the purple sea urchin. It is the type species of the genus and occurs in the Mediterranean Sea and eastern Atlantic Ocean.
Sphaerechinus granularis is a species of sea urchin in the family Toxopneustidae, commonly known as the violet sea urchin, or sometimes the purple sea urchin. Its range includes the Mediterranean Sea and eastern Atlantic Ocean.
Spatangus purpureus, commonly known as the purple heart urchin, is a species of sea urchin in the family Spatangidae. It is found in the eastern Atlantic Ocean and the Mediterranean Sea, where it lives immersed in the sediment.
Arbacia spatuligera is a species of sea urchin of the family Arbaciidae. Its armour is covered with spines. A. lixula was first scientifically described in 1846 by Valenciennes.
Centrostephanus longispinus, the hatpin urchin, is a species of sea urchin in the family Diadematidae. There are two subspecies, Centrostephanus l. longispinus, found in the eastern Atlantic and Mediterranean Sea and Centrostephanus l. rubricingulus, found in the western Atlantic.
Cheilodipterus novemstriatus, the Indian Ocean twospot cardinalfish, is a species of ray-finned fish from the Indian Ocean, which is a member of the family Apogonidae. It has colonised the eastern Mediterranean Sea by way of the Suez Canal since 2011.
Tetrapygus is a genus of sea urchins in the family Arbaciidae. It is a monotypic genus and the only species is Tetrapygus niger which was first described by the Chilean naturalist Juan Ignacio Molina in 1782. It is found in the southeastern Pacific Ocean on the coasts of South America.
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