| Lytechinus variegatus | |
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Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | Echinoidea |
| Order: | Camarodonta |
| Family: | Toxopneustidae |
| Genus: | Lytechinus |
| Species: | L. variegatus |
| Binomial name | |
| Lytechinus variegatus | |
Lytechinus variegatus, commonly called the green sea urchin or the variegated sea urchin, is a species of sea urchin that can be found in the warm waters of the western Atlantic Ocean and Caribbean Sea.
There are four subspecies: [1]
The green sea urchin has a globular test (shell) densely covered in spines and can reach a diameter of around 11 centimetres (4.3 in). The test may be purple, green or dull red, blotched with white. The majority of the spines are short but there are a few longer primary spines. The spines vary in colour, sometimes being one colour at the base and a different colour at the tip. Green test with green spines or green test with white spines are the most common combinations found in the Caribbean. In between the spines are pedicellaria, pincer like structures. These are white which distinguishes the green sea urchin from the rather similar Lytechinus williamsi which has purple pedicellaria. [2] [3]
Echinobase is the model organism database for the painted urchin and a number of other echinoderms.
The green sea urchin occurs in tropical waters in the western Atlantic Ocean. The subspecies occupy different geographical areas. L. v. variegatus occurs in the Caribbean Sea, southern Florida, the Yucatán peninsula and northern Brazil but not Barbados while L. v. carolinus is found from North Carolina southwards to the Caribbean Sea and Gulf of Mexico. It is found on rocky reefs, on or under rocks, on sandy or muddy substrates and in seagrass meadows. It can occur in large numbers with as many as 15 being found in one square metre (yard). [3]
The green sea urchin is often found with pieces of algae, bits of seagrass and fragments of mollusc shell on its aboral (upper) surface, holding them in place with its tube feet. It is thought that the urchin is photo-sensitive and that these pieces of debris may provide some protection from strong sunlight and ultraviolet light in the clear shallow waters it favours. [4] While subsequent research confirmed that a different species, L. pictus (= L. anamesus), submerged in 20-cm deep aquaria responded negatively to sunlight and UV light and succumbed following extended exposure to UV light. However, studies in wave tanks with or without light showed they masked with shell material and aggregated in groups when exposed to surge activity. Masked and/or aggregated urchins were able to remain stable on the sand whereas unmasked individuals rolled around helplessly on the sand. [5]
The green sea urchin has a structure called an Aristotle's lantern surrounding its mouth on its oral (under) surface. This has five teeth that can be used to rasp surfaces. It is largely herbivorous, feeding on the seagrass Thalassia . Its tube feet and spines also play a role in feeding, catching and holding bits of debris that float past. [4]
It is sometimes found in aggregations of closely packed individuals. This may be linked to breeding activities but at other times it has no known cause. [3] Breeding takes place at various times of the year in different parts of its range. In Bermuda the spawning period is short and seems to be related to the phase of the moon. Eggs and sperm are liberated into the water column and fertilisation is external. The larvae are planktonic and are known as pluteus larvae. They pass through several developmental stages before undergoing metamorphosis into juvenile urchins. [4]
The diadema urchin or blue-black urchin is a species of tropical sea urchin, member of the Diadematidae family.
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.
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.
Echinus is a genus of sea urchins. Sea urchins are echinoderms that are typically spherical or flattened with a covering of spine-like structures. Sea urchins tend to be important members of their ecosystems by grazing on other organisms and stabilizing populations. In addition to this, sea urchins play a large role in different economies globally as the urchin themselves and their roe are sold for consumption. The same is true for the species within the genus Echinus.
Tripneustes ventricosus, commonly called the West Indian sea egg or white sea urchin, is a species of sea urchin. It is common in the Caribbean Sea, the Bahamas and Florida and may be found at depths of less than 10 metres (33 ft).
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.
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.
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.
Aspidodiadema jacobyi is a small sea urchin in the family Aspidodiadematidae. It lives in tropical seas at great depths. Aspidodiadema jacobyi was first scientifically described in 1880 by Alexander Emanuel Agassiz, an American scientist.
Several species of sea urchin share the name green sea urchin:
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.
Lytechinus is a genus of sea urchins.
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.
Eucidaris is a genus of cidaroid sea urchins known as slate pencil urchins. They are characterised by a moderately thick test, a usually monocyclic apical disc, perforate and non-crenulate tubercles and nearly straight ambulacra with horizontal pore pairs. The primary spines are few and widely spaced, stout with blunt flat tips and beaded ornamentation and the secondary spines are short and apressed. They originated in the Miocene and extant members of the genus are found in the tropical Indo-Pacific Ocean, East Pacific, Atlantic Ocean and Caribbean Sea.
Clypeaster rosaceus, the fat sea biscuit, is a species of sea urchin in the family Clypeasteridae. It occurs in shallow water in the western Atlantic Ocean and was first scientifically described in 1758 by Carl Linnaeus.
Lytechinus pictus, commonly known as the painted urchin, is a sea urchin in the family Toxopneustidae. It occurs on shallow reefs in the tropical and subtropical eastern Pacific Ocean, off the coasts of California, Central America and South America as far south as Ecuador.
Parechinus angulosus, the Cape urchin, is a sea urchin in the family Parechinidae endemic to southern Africa. It is the only species in the genus Parechinus.
Mespilia globulus, the globular sea urchin, sphere sea urchin, or tuxedo urchin, is a sea urchin occurring in tropical shallow reef habitats. The specific name refers to a small ball or spherule, describing its overall shape/morphology. It is the only species in the genus Mespilia.
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