Echinothurioida

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Echinothurioida
Temporal range: Middle Jurassic–Recent
Fire Urchin Asthenosoma varium.jpg
Fire urchin ( Asthenosoma varium )
Scientific classification
Kingdom:
Animalia
Phylum:
Echinodermata
Class:
Echinoidea
Subclass:
Euechinoidea
Superorder:
Diadematacia
Order:
Echinothurioida

Claus, 1880 [1]
Families
See text

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.

Contents

Characteristics

Echinothurioids have regular tests (shells) with 10 columns of plates. These plates are fused in groups of three with a central primary plate and a half plate on either side. The edge of each group of plates overlaps the next one in the manner of tiles on a roof and this means the test is flexible. These animals usually collapse to a disc shape when brought to the surface. The primary tubercles which articulate with the spines are each perforated by a hole and the spines are hollow. The primary spines are usually long and are used to support the test and in locomotion. In many species, the secondary spines are tipped with poison glands and the urchins should only be handled with gloves. The fused plates continue to the edge of the jaws, covering the peristome membrane that surrounds the mouth. The mouthparts, known as the Aristotle's lantern, have simple plates and grooved teeth. The gills are relatively small, and in many species, entirely absent. [2] [3] [4]

Biology

Toxic leather sea urchin (Asthenosoma marisrubri) Toxic Leather Sea Urchin - Asthenosoma marisrubri.jpg
Toxic leather sea urchin
( Asthenosoma marisrubri )
Gold sea urchin (Tromikosoma sp.) at 2,932 metres (9,619 ft) Expl0867 - Flickr - NOAA Photo Library.jpg
Gold sea urchin ( Tromikosoma sp.)
at 2,932 metres (9,619 ft)
Phormosoma placenta Phormosoma placenta.jpg
Phormosoma placenta
Hygrosoma sp. Deep sea Echinothurioid.jpg
Hygrosoma sp.

Echinothurioids are nearly all found on the seabed at abyssal depths, but by way of an exception, Asthenosoma ijimai is found in shallow water. [2] Because of the difficulty in studying these echinothurioids at such depths, little is known of their feeding habits, but examination of their stomach contents suggests they eat detritus, mostly in the form of algal fragments. Their reproduction is also relatively unstudied, but some members of the group, such as Phormosoma placenta , produce eggs with large yolks which at first rise towards the surface and later sink again. The bilaterally symmetrical larva, called an echinopluteus, is planktonic and may not feed, relying on its yolk for nourishment before descending to the seabed and undergoing metamorphosis. [2] [4]

Evolutionary history

For many years, echinothurioids were believed to be extinct, being only known from fossils. These are found infrequently because the test tends to disintegrate after the echinoderm dies and the only parts to be preserved are detached plates and spines. The earliest known echinothurioid was Pelanechinus , dating back to the Middle to Late Jurassic. It had a more fused test than more recent species and was better preserved. [2] It bridges the gap between the echinothurioids and the diadematioids. [5] The earliest crown group example was Echinothuria, which came from the Upper Cretaceous of southern England. Living members of the group were found after the Challenger expedition of 1872–76 began to explore the deep sea. [2]

Taxonomy

The World Echinoidea Database recognises these families and genera: [1]

"†" means an extinct taxon

See also

Related Research Articles

<span class="mw-page-title-main">Sea urchin</span> Class of marine invertebrates

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.

<i>Coelopleurus</i> Extinct genus of sea urchins

Coelopleurus is an extant genus of echinoids with fossil records dating back to the Eocene, with remains found in Europe and North America.

<span class="mw-page-title-main">Temnopleuridea</span> Infraorder of sea urchins

Temnopleuridea is an infraorder of sea urchins in the order Camarodonta. They are distinguished from other sea urchins by the presence of large fused plates on top of the feeding lantern. The test is usually sculpted to some degree, and has perforated tubercles.

<span class="mw-page-title-main">Camarodonta</span> Order of sea urchins

The Camarodonta are an order of globular sea urchins in the class Echinoidea. The fossil record shows that camarodonts have been in existence since the Lower Cretaceous.

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.

<i>Asthenosoma varium</i> Species of sea urchin

Asthenosoma varium is a sea urchin. Growing up to 25 cm (10 in) in diameter, it lives on sand and rubble sea bottoms in the Indo-Pacific, from the Red Sea to Australia and Southern Japan. Its venom tipped spines, with distinctive globular swellings below the tip, can inflict a painful sting if handled; the pain lasts as long as several hours. This capacity, perhaps coupled with its reddish-brown colour, has given it the common name fire urchin; other commonly used names are Pacific fire urchin, elusive sea urchin, variable fire urchin, and electric sea urchin.

Araeosoma alternatum is a species of sea urchin of the family Echinothuriidae. Their armour is covered with spines. It is placed in the genus Araeosoma and lives in the sea. Araeosoma alternatum was first scientifically described in 1934 by Ole Theodor Jensen Mortensen, a Danish zoologist.

Araeosoma belli is a species of sea urchin of the family Echinothuriidae. Their armour is covered with spines. It is placed in the genus Araeosoma and is found throughout the Caribbean Sea as well as areas around the Gulf of Mexico. Araeosoma belli was first scientifically described in 1903 by Ole Theodor Jensen Mortensen, a Danish zoologist.

<i>Araeosoma owstoni</i> Species of sea urchin

Araeosoma owstoni is a species of sea urchin of the family Echinothuriidae. Their armour is covered with spines. It is placed in the genus Araeosoma and lives in the sea. Araeosoma owstoni was first scientifically described in 1904 by Ole Theodor Jensen Mortensen.

<i>Araeosoma parviungulatum</i> Species of sea urchin

Araeosoma parviungulatum is a species of sea urchin of the family Echinothuriidae. Their armour is covered with spines. It is placed in the genus Araeosoma and lives in the sea. Araeosoma parviungulatum was first scientifically described in 1934 by Ole Theodor Jensen Mortensen.

Araeosoma splendens is a species of sea urchin of the family Echinothuriidae. Their armour is covered with spines. It is placed in the genus Araeosoma and lives in the sea. Araeosoma splendens was first scientifically described in 1934 by Ole Theodor Jensen Mortensen.

Araeosoma violaceum is a species of sea urchin of the family Echinothuriidae. Its armour is covered with spines. It is placed in the genus Araeosoma and lives in the sea. A. violaceum was first scientifically described in 1903 by Ole Theodor Jensen Mortensen.

Asthenosoma dilatatum is a species of sea urchin of the family Echinothuriidae. Their armour is covered with spines. It is placed in the genus Asthenosoma and lives in the sea. Asthenosoma dilatatum was first scientifically described in 1934 by Ole Theodor Jensen Mortensen.

Calveriosoma gracile is a species of sea urchin in the order Echinothurioida. It is a deep water species and is found on the seabed in western parts of the Pacific Ocean at depths of 200 to 800 metres.

Pelanechinus is an extinct genus of sea urchins in the order Echinothurioida. It is placed in the family Pelanechinidae and is in the stem group of echinoids.

<i>Phormosoma placenta</i> Species of sea urchin

Phormosoma placenta is a species of sea urchin in the order Echinothurioida. It is a deepwater species, seldom being found at depths less than 500 m (1,600 ft), and occurs on either side of the Atlantic Ocean on the continental slope.

<span class="mw-page-title-main">Echinothuriidae</span> Family of sea urchins

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.

<i>Asthenosoma</i> Genus of sea urchins

Asthenosoma is a genus of sea urchins in the family Echinothuriidae. Their spines are covered with harmful venom capsules.

<i>Araeosoma</i> Genus of sea urchins

Araeosoma is a genus of deep-sea sea urchins in the family Echinothuriidae.

<i>Dermechinus</i> Genus of sea urchins

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.

References

  1. 1 2 Kroh, Andreas (2012). Kroh A, Mooi R (eds.). "Echinothurioida". World Echinoidea Database. World Register of Marine Species . Retrieved 2012-12-07.
  2. 1 2 3 4 5 "Order Echinothurioida Claus, 1880". The Echinoid Directory. The Natural History Museum. Retrieved 2012-12-07.
  3. ↑ Serafy, D. Keith; Fell, F. Julian (1985). "Marine Flora and Fauna of the Northeastern United States. Echinodermata: Echinoidea" (PDF). NOAA Technical Report NMFS 33. Retrieved 2012-12-30.
  4. 1 2 Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 980. ISBN   0-03-056747-5.
  5. ↑ Groom, T. T. (1887). "On some New Features in Pelanechinus corallinus". Quarterly Journal of the Geological Society. 43 (1–4): 703–714. doi:10.1144/GSL.JGS.1887.043.01-04.53. S2CID   129510392.
  6. ↑ Kroh, Andreas; Smith, A. B. (2010). "The phylogeny and classification of post-Palaeozoic echinoids" (PDF). Journal of Systematic Palaeontology. 8 (2): 147–212. doi: 10.1080/14772011003603556 . S2CID   55961732.
  7. ↑ Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (Echinoidea)". Bulletins of American Paleontology. 364: 560. Retrieved 2012-12-08.
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