| Gracilechinus | |
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| Gracilechinus acutus at the Biodiversarium of the Observatoire océanologique de Banyuls-sur-Mer | |
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| Genus: | Gracilechinus Fell & Pawson, 1966 |
| Species | |
see text | |
Gracilechinus is a genus of sea urchins in the family Echinidae.
The species in this genus are regular sea urchins, with a rounded test, bearing the anus at the top and the mouth at the bottom. They are extremely similar to species in the genus Echinus , but are differentiated by a primary tubercle on every interambulacral plate. [1]
Most species in this genus are abyssal, and live in the North Atlantic or close cold seas.
Species in this genus include: [2]
| Image | Scientific name | Distribution |
|---|---|---|
 | Gracilechinus acutus (Lamarck, 1816) | Europe (Mediterranean and Atlantic) |
| Gracilechinus affinis (Mortensen, 1903) | center Atlantic | |
| Gracilechinus alexandri (Döderlein & Koren, 1883) | Northern Atlantic | |
| Gracilechinus atlanticus (Mortensen, 1903) | Atlantic | |
| Gracilechinus elegans (Düben & Koren, 1844) | North-east Atlantic | |
 | Gracilechinus gracilis (Agassiz, 1869) | Caribbean |
 | Gracilechinus lucidus (Döderlein, 1885) | North-west Pacific |
| Gracilechinus stenoporus (Mortensen, 1942) | South Africa | |
Diadema is a genus of sea urchins of the family Diadematidae.
Agassizia is a genus of sea urchin of the family Prenasteridae. The species was first scientifically described in 1869 by Achille Valenciennes.
Strongylocentrotus is a genus of sea urchins in the family Strongylocentrotidae containing several species.
Cassiduloida is an order of sea urchins. The group was extremely diverse with many families and species during the Mesozoic, but today, only seven extant species remain.
The Echinothurioida are an order of sea urchins in the class Echinoidea. Echinothurioids are distinguished from other sea urchins by the combination of a flexible test and hollow spines. The membrane around the mouth contains only simple plates, in contrast to the more complex mouth parts of their close relatives, the Diadematoida. They are nearly all deepsea dwellers.
Amblypneustes leucoglobus is a species of sea urchin of the family Temnopleuridae. Their armour is covered with spines. It came from the genus Amblypneustes and lives in the sea. Amblypneustes leucoglobus was first scientifically described in 1914 by Ludwig Döderlein.
Aporocidaris usarpi is a species of sea urchin of the family Ctenocidaridae. Their armour is covered with spines. It is placed in the genus Aporocidaris and lives in the sea. Aporocidaris usarpi was first scientifically described in 2000 by Mooi, David, Fell & Choné.
Toxopneustes is a genus of sea urchins from the tropical Indo-Pacific. It contains four species. They are known to possess medically significant venom to humans on their pedicellariae. They are sometimes collectively known as flower urchins, after the most widespread and most commonly encountered species in the genus, the flower urchin.
Echinometra is a genus of sea urchins in the family Echinometridae.
Aspidodiadema montanum is a species of sea urchin of the family Aspidodiadematidae. Their armour is covered with spines. It is placed in the genus Aspidodiadema and lives in the sea. Aspidodiadema montanum was first scientifically described in 1981 by Mironov.
Astriclypeus mannii is a species of sea urchin of the family Astriclypeidae. Their armour is covered with spines. It is placed in the genus Astriclypeus and lives in the sea. Astriclypeus mannii was first scientifically described in 1867 by Verrill.
Cidaris blakei is a species of sea urchins of the family Cidaridae. Its armour is covered with spines of three types, one unique type being extended and fan-like, making it easily recognized. Alexander Agassiz first described it scientifically in 1878. It is present on the seabed in deep waters in the Gulf of Mexico and the Bahamas.
The Echinothuriidae are a family of sea urchins in the order Echinothurioida. Due to their soft skeletons, most are called "leather urchins", but species in the genus Asthenosoma are also known as "fire urchins" due to their bright colors and painful, venomous sting.
Toxopneustes roseus is a species of sea urchin from the East Pacific. It is sometimes known as the rose flower urchin or the pink flower urchin. Like the related flower urchin, they are venomous.
Toxopneustes elegans is a species of sea urchin endemic to Japan. Like the closely related flower urchin, they are venomous.
Chondrocidaris is a genus of sea urchins of the family Cidaridae described in 1863 by Alexander Agassiz. There are two living species and several fossil species dating as far back as the Miocene.
Araeosoma is a genus of deep-sea sea urchins in the family Echinothuriidae.
Tetragramma is a genus of fossil sea urchins known from the Upper Jurassic (Oxfordian) to the Upper Cretaceous (Turonian).
Dermechinus is a genus of sea urchin in the family Echinidae found in deep water in the southern Indian, Pacific and Atlantic Oceans. It is monotypic, with Dermechinus horridus, sometimes called the cactus urchin, being the only species.
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.