Sea Urchin
The sea urchin Strongylocentrotus purpuratus in an aquarium
Scientific classification
Kingdom: Animalia Phylum: Echinodermata Subphylum: Echinozoa Class: Echinoidea Leske, 1778
Subclasses
Subclass Perischoechinoidea Order Cidaroida (pencil urchins) Subclass Euechinoidea Superorder Atelostomata Order Cassiduloida Order Spatangoida (heart urchins) Superorder Diadematacea Order Diadematoida Order Echinothurioida Order Pedinoida Superorder Echinacea Order Arbacioida Order Echinoida Order Phymosomatoida Order Salenioida Order Temnopleuroida Superorder Gnathostomata Order Clypeasteroida (sand dollars) Order Holectypoida

Wikispecies has information related to:

Echinoidea

Sea Urchins are small, spiny sea creatures of the class Echinoidea found in oceans all over the world. (The name urchin is an old name for the round spiny hedgehogs sea urchins resemble.) Their shell, which is also called the "test", is globular in shape and covered with spines. The size of an adult test is typically from 3 to 10 cm. Image File history File links Metadata Size of this preview: 800 × 600 pixelsFull resolution‎ (2,560 × 1,920 pixels, file size: 2. ... Strongylocentrotus purpuratus. ... Scientific classification or biological classification refers to how biologists group and categorize extinct and living species of organisms. ... For other uses, see Animal (disambiguation). ... Classes Asteroidea Concentricycloidea Crinoidea Echinoidea Holothuroidea Ophiuroidea Echinoderms (Echinodermata) is a phylum of marine animals found in the ocean at all depths. ... Leske, Nathanael Gottfried (22 October 1751 in Muskau- 25 November 1786 in Marburg was a natural scientist and geologist. ... NOTE - UNDER CONSTRUCTION Infra Class Acroechinoidea Infra Class Echinothurioidea Categories: Equinodermata taxonomy ... ... Suborders Clypeasterina Laganina Rotulina Scutellina The common sand dollar is the skeleton or test of a marine animal. ... Image File history File links Wikispecies-logo. ... Wikispecies is a wiki-based online project supported by the Wikimedia Foundation that aims to create a comprehensive free content catalogue of all species (including animalia, plantae, fungi, bacteria, archaea, and protista). ... Urchin is the old English term for hedgehog. ... This article is about the spiny mammal. ...

Typical sea urchins have spines that are 1 to 3 cm in length, 1 to 2 mm thick, and not terribly sharp. Diadema antillarum, familiar in the Caribbean, has thin spines that can be 10 to 20 cm long. Common colors include black and dull shades of green, olive, brown, purple, and red.

Sea urchins are members of the phylum Echinodermata, which also includes starfish, sea cucumbers, brittle stars, and crinoids. Like other echinoderms they have fivefold symmetry (called pentamerism) and move by means of hundreds of tiny, transparent, adhesive "tube feet". The pentamerous symmetry is not obvious at a casual glance but is easily seen in the dried shell or test of the urchin. Subphyla & Classes Homalozoa Gill & Caster, 1960 Homostelea Homoiostelea Stylophora † Ctenocystoidea Robison & Sprinkle, 1969 Crinozoa Crinoidea Paracrinoidea † Regnéll, 1945 Cystoidea †von Buch, 1846 Asterozoa Ophiuroidea Asteroidea Echinozoa Echinoidea Holothuroidea Ophiocistioidea Helicoplacoidea † Arkarua † Homalozoa † Pelmatozoa † Edrioasteroidea † Blastozoa † Blastoidea † Eocrinoidea †Jaekel, 1899 † = extinct Echinoderms (Phylum Echinodermata, from the Greek for spiny skin... Orders Brisingida (100 species[1]) Forcipulatida (300 species[2]) Paxillosida (255 species[3]) Notomyotida (75 species[4]) Spinulosida (120 species[5]) Valvatida (695 species[6]) Velatida (200 species[7]) For other uses, see Starfish (disambiguation). ... Orders Subclass Apodacea Apodida Molpadiida Subclass Aspidochirotacea Aspidochirotida Elasipodida Subclass Dendrochirotacea Dactylochirotida Dendrochirotida Wikispecies has information related to: Holothuroidea The sea cucumber is an echinoderm of the class Holothuroidea, with an elongated body and leathery skin, which is found on the sea floor worldwide. ... Orders ME Oegophiurida Ophiurida Phrynophiurida Brittle stars are echinoderms, closely related to starfish. ... Subclasses Articulata (540 species) Cladida (extinct) Flexibilia (extinct) Camerata (extinct) Disparida (extinct) Crinoids, also known as sea lilies or feather-stars, are marine animals that make up the class Crinoidea of the echinoderms (phylum Echinodermata). ... The elaborate patterns on the wings of butterflies are one example of bilateral symmetry. ... The tube feet can be clearly seen on this sea star Tube feet are the many small tubular projections found most famously on the ventral face of a sea stars arms, but are characteristic of the water vascular system of the echinoderm phylum which also includes sea urchins, sand...

Together with sea cucumbers (Holothuroidea), they make up the subphylum Echinozoa, which is defined by primarily having a globoid shape without arms or projecting rays, even if the sea cucumbers and the irregular echinoids have secondarily-evolved different shapes. Although many sea cucumbers have branched tentacles surrounding the oral opening, these have originated from modified tube feet and are not homologous to the arms of the crinoids, starfish and brittle stars.

Within the echinoderms, sea urchins are classified as echinoids (class Echinoidea). Specifically, the term "sea urchin" refers to the "regular echinoids," which are symmetrical and globular. The ordinary phrase "sea urchin" actually includes several different taxonomic groups: the Echinoida and the Cidaroida or "slate-pencil urchins", which have very thick, blunt spines (see image at right), and others (see taxonomic box on the right). Besides sea urchins, the Echinoidea also includes three groups of "irregular" echinoids: flattened sand dollars, sea biscuits, and heart urchins. Suborders and families See text. ... Seabiscuit may refer to one of the following: Seabiscuit, the champion thoroughbred race horse; Seabiscuit: An American Legend, a book by Laura Hillenbrand about the horse of the same name; Seabiscuit (film), a 2003 film about the horse, based on Hillenbrands book; seabiscuit, another name for a sand dollar...

Physiology

At first glance, a sea urchin often appears to be an inanimate object, or one that is incapable of moving. Sometimes the most visible sign of life is the spines, which are attached at their bases to ball-and-socket joints and can be pointed in any direction. In most urchins, a light touch elicits a prompt and visible reaction from the spines, which converge toward the point that has been touched. A sea urchin has no visible eyes, legs or means of propulsion, but it can move freely over surfaces by means of its adhesive tube feet, working in conjunction with its spines.

On the oral surface of the sea urchin is a centrally located mouth made up of five united calcium carbonate teeth or jaws, with a fleshy tongue-like structure within. The entire chewing organ is known as Aristotle's lantern. The name comes from Aristotle's accurate description in his History of Animals: Calcium carbonate is a chemical compound, with the chemical formula CaCO3. ... For other uses, see Aristotle (disambiguation). ...

...the urchin has what we mainly call its head and mouth down below, and a place for the issue of the residuum up above. The urchin has, also, five hollow teeth inside, and in the middle of these teeth a fleshy substance serving the office of a tongue. Next to this comes the esophagus, and then the stomach, divided into five parts, and filled with excretion, all the five parts uniting at the anal vent, where the shell is perforated for an outlet... In reality the mouth-apparatus of the urchin is continuous from one end to the other, but to outward appearance it is not so, but looks like a horn lantern with the panes of horn left out. (Tr. D'Arcy Thompson)

The spines, which in some species are long and sharp, serve to protect the urchin from predators. The spines can inflict a painful wound on a human who steps on one, but they are not seriously dangerous, and it is not clear that the spines are truly venomous (unlike the pedicellariae between the spines, which are venomous). DArcy Wentworth Thompson (May 2, 1860- June 21, 1948) was a biologist and mathematician and the author of the 1917 book, On Growth and Form, an influential work of striking originality. ... Raised thorns on the stem of the wait-a-bit climber Thorns on rose stems A spine is a rigid, pointed surface protuberance or needle-like structure on an animal, shell, or plant, presumably serving as a defense against attack by predators. ... This snapping turtle is trying to make a meal of a Canada goose, but the goose is too wary. ...

Diet

Echinothrix calamaris, a species of sea urchin. The sphere in the middle of a sea urchin is its anus

Sea urchins feed mainly on algae, but can also feed on a wide range of invertebrates such as mussels, sponges and brittle stars. Sea urchin is one of the favorite foods of sea otters and are also the main source of nutrition for wolf eels. Left unchecked, urchins will devastate their environment, creating what biologists call an urchin barren, devoid of macroalgae and associated fauna. Where sea otters have been re-introduced into British Columbia, the health of the coastal ecosystem has improved dramatically.^[1] Image File history File links Metadata Size of this preview: 800 × 600 pixelsFull resolution (1632 × 1224 pixel, file size: 1. ... Image File history File links Metadata Size of this preview: 800 × 600 pixelsFull resolution (1632 × 1224 pixel, file size: 1. ... Binomial name Pallas, 1774 The double spined urchin or banded sea urchin, Echinothrix calamaris, is a urchin, with a test (shell) diameter of about 5 cm. ... Osborne (talk) 20:17, 5 December 2007 (UTC):For the programming language, see algae (programming language) Laurencia, a marine red alga from Hawaii. ... Binomial name Enhydra lutris (Linnaeus, 1758) The Sea Otter (Enhydra lutris) is a large otter native to the North Pacific, from northern Japan and Kamchatka west across the Aleutian Islands south to California. ... Binomial name Linnaeus, 1758 The Seawolf (Anarhichas lupus), also known as the Atlantic wolffish, Atlantic catfish, wolf eel, or sea cat, is a marine fish, the largest of the family Anarhichadidae. ... An urchin barren is an area in the open sea where the population growth of sea urchins has gone unchecked, causing massive kelp die-offs. ... Motto: Splendor sine occasu (Latin: Splendour without diminishment) Capital Victoria Largest city Vancouver Official languages English (de facto) Government Lieutenant-Governor Steven Point Premier Gordon Campbell (BC Liberal) Federal representation in Canadian Parliament House seats 36 Senate seats 6 Confederation July 20, 1871 (6th province) Area  Ranked 5th Total 944...

Geological history

This section does not cite any references or sources. (November 2006) Please improve this section by adding citations to reliable sources. Unverifiable material may be challenged and removed.

Fossil sea urchin Lovenia woodsi from the Pliocene of Australia.

The earliest known echinoids are found in the rock of the upper part of the Precambrian period, and they have survived to the present day, where they are a successful and diverse group of organisms. In well-preserved specimens the spines may be present, but usually only the test is found. Sometimes isolated spines are common as fossils. Some echinoids (such as Tylocidaris clavigera, which is found in the Cretaceous period Chalk Formation of England) had very heavy club-shaped spines that would be difficult for an attacking predator to break through and make the echinoid awkward to handle. Such spines are also good for walking on the soft sea-floor. Image File history File links Question_book-3. ... Photograph of the fossil echinoid Lovenia taken by Dlloyd. ... Photograph of the fossil echinoid Lovenia taken by Dlloyd. ... The Pliocene epoch (spelled Pleiocene in some older texts) is the period in the geologic timescale that extends from 5. ... The Precambrian (Pre-Cambrian) is an informal name for the supereon comprising the eons of the geologic timescale that came before the current Phanerozoic eon. ... // The Cretaceous Period (pronounced ) is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic Period (i. ... The Chalk Formations of Europe are thick deposits of chalk, a soft porous white limestone, deposited in a marine environment during the upper Cretaceous Period. ... For other uses, see England (disambiguation). ...

Cretaceous echinoids from Castle Hayne quarry, North Carolina, USA

Complete fossil echinoids from the Paleozoic era are generally rare, usually consisting of isolated spines and small clusters of scattered plates from crushed individuals. Most specimens occur in rocks from the Devonian and Carboniferous periods. The shallow water limestones from the Ordovician and Silurian periods of Estonia are famous for the echinoids found there. The Paleozoic echinoids probably inhabited relatively quiet waters. Because of their thin test, they would certainly not have survived in the turbulent wave-battered coastal waters inhabited by many modern echinoids today. During the upper part of the Carboniferous period, there was a marked decline in echinoid diversity, and this trend continued into the Permian period. They neared extinction at the end of the Paleozoic era, with just six species known from the Permian period. Only two separate lineages survived the massive extinction of this period and into the Triassic: the genus Miocidaris, which gave rise to the modern cidaroids (pencil urchins), and the ancestor that gave rise to the euechinoids. By the upper part of the Triassic period, their numbers began to increase again. The cidaroids have changed very little since their modern design was established in the Late Triassic and are today considered more or less as living fossils. The euechinoids, on the other hand, diversified into new lineages throughout the Jurassic period and into the Cretaceous period, and from them emerged the first irregular echinoids (superorder Atelostomata) during the early Jurassic, and when including the other superorder (Gnathostomata) or irregular urchins which evolved independently later, they now represent 47% of all present species of echinoids thanks to their adaptive breakthroughs in both habit and feeding strategy, which allowed them to exploit habitats and food sources unavailable to regular echinoids. During the Mesozoic and Cenozoic eras the echinoids flourished. While most echinoid fossils are restricted to certain localities and formations, where they do occur, they are quite often abundant. An example of this is Enallaster, which may be collected by the thousands in certain outcrops of limestone from the Cretaceous period in Texas. Many fossils of the Late Jurassic Plesiocidaris still have the spines attached. Image File history File links Echinoids-castleHainNC.jpg Summary Echinoid fossils from Castle Hain North Carolina, collected and photographed by me, User Debivort, 2001. ... Image File history File links Echinoids-castleHainNC.jpg Summary Echinoid fossils from Castle Hain North Carolina, collected and photographed by me, User Debivort, 2001. ... // The Cretaceous Period (pronounced ) is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic Period (i. ... Official language(s) English Capital Raleigh Largest city Charlotte Largest metro area Charlotte metro area Area  Ranked 28th  - Total 53,865 sq mi (139,509 km²)  - Width 150 miles (240 km)  - Length 560[1] miles (900 km)  - % water 9. ... For other uses, see Fossil (disambiguation). ... The Paleozoic Era (from the Greek palaio, old and zoion, animals, meaning ancient life) is the earliest of three geologic eras of the Phanerozoic eon. ... For the Celtic language, see Southwestern Brythonic language; for the residents of the English county, see Devon. ... President Bush- Deres gold in dem dere mines The Carboniferous is a major division of the geologic timescale that extends from the end of the Devonian period, about 359. ... For other uses, see Silurian (disambiguation). ... The Permian is a geologic period that extends from about 299. ... The Triassic is a geologic period that extends from about 251 ± 0. ... The Jurassic Period is a major unit of the geologic timescale that extends from about 199. ... Mesozoic Era is one of three geologic eras of the Phanerozoic eon. ... Mammals are the dominant creatures of Cenozoic. ... For other uses, see Limestone (disambiguation). ... For other uses, see Texas (disambiguation). ... Upper Jurassic (also known as Malm) was an epoch of the Jurassic geologic period. ... Binomial name Plesiocidaris durandi Plesiocidaris durandi is an extinct species of sea urchin. ...

Some echinoids, such as Micraster which is found in the Cretaceous period Chalk Formation of England and France, serve as zone or index fossils. Because they evolved rapidly over time, such fossils are useful in enabling geologists to date the rocks in which they are found. However, most echinoids are not abundant enough and may be too limited in their geographic distribution to serve as zone fossils. The Chalk Formations of Europe are thick deposits of chalk, a soft porous white limestone, deposited in a marine environment during the upper Cretaceous Period. ... For other uses, see England (disambiguation). ... Index fossils (or zone fossils) are fossils used to define and identify geologic periods (or faunal stages). ...

The order of clypeasteroids arose in the early Tertiary and is the newest branch on the echinoid tree.

Trivia

Trivia sections are discouraged under Wikipedia guidelines. The article could be improved by integrating relevant items and removing inappropriate ones.

Sea urchins are one of the traditional model organisms in developmental biology. The use of sea urchins in this context originates from the 1800's, when the embryonic development of the sea urchins was noticed to be particulary easily viewed by microscopy. Sea urchins were the first species, in which the sperm cells were proven to play an important role in reproduction by fertilizing the ovum. Image File history File links Broom_icon. ... Views of a Foetus in the Womb, Leonardo da Vinci, ca. ... For other uses, see Sperm (disambiguation). ... For other uses, see Reproduction (disambiguation) Reproduction is the biological process by which new individual organisms are produced. ... A human ovum Sperm cells attempting to fertilize an ovum An ovum (plural ova) is a haploid female reproductive cell or gamete. ...

Gallery

Group of black, long-spined Caribbean sea urchins (Diadema antillarum (Philippi)). Diadema antillarium (black spiny Caribbean sea urchin) Photograph taken by Daniel P. B. Smith. ...	Sea urchin roe. Sea urchin disected and about to be devoured. ... This article is about fish eggs. ...	Sea urchin test. Each white band is the location of a row of tube feet; each pair of white bands is called an acubolum. There are five such acubolum; the fivefold symmetry reveals a kinship with starfish. Image File history File linksMetadata Zeeegel3. ...	Closeup of test. In life, a tube foot or gill extends through each of the small holes, and a spine is supported by each of the raised tubercles. Image File history File links Size of this preview: 724 × 600 pixelsFull resolution‎ (1,024 × 848 pixels, file size: 295 KB, MIME type: image/jpeg)Close-up of a sea urchin test (the shell). ...
Sea urchins have adhesive tube feet. Image File history File links Download high resolution version (616x616, 80 KB) todo o animal, das ganze Tier, the whole animal Português purmenor dum ouriço do mar (Echinoidea) na Galiza fotografado por Janek Pfeifer 10. ...	Sea urchin in a reef off of the Florida coast. Image File history File links Metadata Size of this preview: 450 × 600 pixelsFull resolution‎ (1,944 × 2,592 pixels, file size: 1. ...	Sea urchins in California tide pools This article is about the U.S. state. ... A tide pool on Gabriola Island, British Columbia showing ochre sea stars Tide pools (also tidal pools or rock pools) are rocky pools by oceans that are filled with seawater. ...

References and further reading

• Smith, Andrew B. (1984), Echinoid Palaeobiology (Special topics in palaeontology). London: Allen & Unwin. ISBN 0-04-563001-1

http://animaldiversity.ummz.umich.edu/site/accounts/classification/Echinoidea.html#Echinoidea Animal Diversity Web Classification of the Echinoidea]

http://whale.wheelock.edu/archives/ask99/0388.html#The Ocean Alliance giving advice on sea urchin cleaning]

1. ^ Aquatic Species at Risk - Species Profile - Sea Otter. Fisheries and Oceans Canada. Retrieved on 2007-11-29.

The Department of Fisheries and Oceans (DFO), also referred to as Fisheries and Oceans Canada (Pêches et Océans Canada), is the department within the government of Canada with responsibility for the management and safety of waters under federal jurisdiction. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 333rd day of the year (334th in leap years) in the Gregorian calendar. ...

External links

Wikimedia Commons has media related to:

Sea urchin

• Sea Urchin Harvesters Association - California
• The Echinoid Directory from the Natural History Museum.
• 70% of Sea Urchin Genes Have a Human Counterpart -- Sequencing confirms that sea urchins are more closely related to humans than fruit flies (LiveScience.com, November 2006).
• Spiny creature's genome insight
• Echinoids.nl
• lantern.jpg A labeled diagram of the sea urchin's Aristotle's lantern.
• aristotle.htm Who is this person Aristotle and what about this lantern?
• www.emilydamstra.com Illustration of the musculature of an Aristotle's lantern.Image:Sea urchin.bmp{{Taxobox