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Encyclopedia > Sea anemone
Sea anemone
Sea anemone at the Monterey Bay Aquarium
Sea anemone at the Monterey Bay Aquarium
Scientific classification
Kingdom: Animalia
Phylum: Cnidaria
Class: Anthozoa
Subclass: Hexacorallia
Order: Actiniaria
Diversity
46 families
Suborders

Endocoelantheae
Nyantheae
Protantheae
Ptychodacteae Image File history File links Download high-resolution version (2608x1820, 1754 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Sea anemone ... This article does not cite any references or sources. ... For other uses, see Scientific classification (disambiguation). ... For other uses, see Animal (disambiguation). ... Subphylum/Classes[1] Anthozoa — corals and sea anemones Medusozoa:[2] Cubozoa — sea wasps or box jellyfish Hydrozoa — hydroids, hydra-like animals Polypodiozoa Scyphozoa — jellyfish Staurozoa — stalked jellyfish unranked: Myxozoa - parasites Cnidaria[3] (IPA: [4]) is a phylum containing some 11,000 species of apparently simple animals found exclusively in aquatic... Anthozoa is a class within the phylum Cnidaria that contains the sea anemones and corals. ... Zoantharia (also known as Hexacorallia, as they have 6-fold symmetry) is a subclass of the class Anthozoa within the phylum Cnidaria. ... The Actiniaria is the order of animals in the class Anthozoa that includes sea anemones. ...

The 49th plate from Ernst Haeckel's Kunstformen der Natur, 1904, showing various sea anemones classified as Actiniae
The 49th plate from Ernst Haeckel's Kunstformen der Natur, 1904, showing various sea anemones classified as Actiniae

Sea anemones are a group of water dwelling, predatory animals of the order Actiniaria; they are named after the anemone, a terrestrial flower. As cnidarians, sea anemones are closely related to corals, jellyfish, tube-dwelling anemones and Hydra. Image File history File links Download high-resolution version (2276x3244, 2258 KB) HOOP The 49th plate from Ernst Haeckels Kunstformen der Natur of 1904, showing various sea anemones classified as Actiniae. ... Image File history File links Download high-resolution version (2276x3244, 2258 KB) HOOP The 49th plate from Ernst Haeckels Kunstformen der Natur of 1904, showing various sea anemones classified as Actiniae. ... Ernst Haeckel. ... The 8th print, Discomedusae. ... This snapping turtle is trying to make a meal of a Canada goose, but the goose is too wary. ... In scientific classification used in biology, the order (Latin: ordo, plural ordines) is a rank between class and family (termed a taxon at that rank). ... Species see text Anemone (Anemone) (from the Gr. ... For other uses, see Flower (disambiguation). ... Subphylum/Classes[1] Anthozoa — corals and sea anemones Medusozoa:[2] Cubozoa — sea wasps or box jellyfish Hydrozoa — hydroids, hydra-like animals Polypodiozoa Scyphozoa — jellyfish Staurozoa — stalked jellyfish unranked: Myxozoa - parasites Cnidaria[3] (IPA: [4]) is a phylum containing some 11,000 species of apparently simple animals found exclusively in aquatic... Extant Subclasses and Orders Alcyonaria    Alcyonacea    Helioporacea Zoantharia    Antipatharia    Corallimorpharia    Scleractinia    Zoanthidea [1][2]  See Anthozoa for details For other uses, see Coral (disambiguation). ... Bold text For other uses, see Jellyfish (disambiguation). ... The Tube-dwelling anemone is a close relation of the Sea Anemone. ... Species Hydra americana Hydra attenuata (or Hydra vulgaris) Hydra canadensis Hydra carnea Hydra cauliculata Hydra circumcincta Hydra hymanae Hydra littoralis Hydra magnipapillata Hydra minima Hydra oligactis Hydra oregona Hydra pseudoligactis Hydra rutgerensis Hydra utahensis Hydra viridis Hydra viridissima Hydra is a genus of simple, fresh-water animals possessing radial symmetry. ...

Contents

Anatomy

Sea anemones engaged in clone war
Sea anemones engaged in clone war

A sea anemone is a small sac, attached to the bottom by an adhesive foot, with a column shaped body ending in an oral disc. The mouth is in the middle of the oral disc, surrounded by tentacles armed with many cnidocytes, which are cells that function as a defense and as a means to capture prey. Cnidocytes contain cnidae, capsule-like organelles capable of everting, giving phylum Cnidaria its name [1]. The cnidae that sting are called nematocysts. Each nematocyst contains a small vesicle filled with toxins—actinoporins—an inner filament and an external sensory hair. When the hair is touched, it mechanically triggers the cell explosion, a harpoon-like structure which attaches to organisms that trigger it, and injects a dose of poison in the flesh of the aggressor or prey. This gives the anemone its characteristic sticky feeling. Image File history File links Size of this preview: 662 × 600 pixelsFull resolution (1000 × 906 pixel, file size: 616 KB, MIME type: image/jpeg) Sea Anemones are engaged in a clone war. ... Image File history File links Size of this preview: 662 × 600 pixelsFull resolution (1000 × 906 pixel, file size: 616 KB, MIME type: image/jpeg) Sea Anemones are engaged in a clone war. ... Nomarski micrograph of a Ruthenium-red stained nematocyst from Aiptasia pallida, the pale anemone. ... Schematic of typical animal cell, showing subcellular components. ... Cnidocytes are prey-capture and defensive cells unique to animals of the phylum Cnidaria. ... Actinotoxin is a poison derived from extracts of the tentacles of sea anemones. ...


The poison is a mix of toxins, including neurotoxins, which paralyze the prey, which is then moved by the tentacles to the mouth/anus for digestion inside the gastrovascular cavity. Actinoporins have been reported as highly toxic to fish and crustaceans, which may be the natural prey of sea anemones. In addition to their role in predation, it has been suggested that actinoporins could act, when released in water, as repellents against potential predators. Clownfish are immune to an anemone's sting. For a list of biologically injurious substances, including toxins and other materials, as well as their effects, see poison. ... A neurotoxin is a toxin that acts specifically on nerve cells, or neurons, usually by interacting with membrane proteins and ion channels. ... For the Dutch band, see Crustacean (band). ... Species See text. ...


The internal anatomy of anemones is simple. There is a gastrovascular cavity (which functions as a stomach) with a single opening to the outside which functions as both a mouth and an anus: waste and undigested matter is excreted through the mouth/anus. A primitive nervous system, without centralization, coordinates the processes involved in maintaining homeostasis as well as biochemical and physical responses to various stimuli. Anemones range in size from less than 1¼ cm (½ in) to nearly 2 m (6 ft) in diameter.[citation needed] They can have a range of 10 tentacles to hundreds. A centimetre (American spelling centimeter, symbol cm) is a unit of length that is equal to one hundredth of a metre, the current SI base unit of length. ... An inch (plural: inches; symbol or abbreviation: in or, sometimes, ″ - a double prime) is the name of a unit of length in a number of different systems, including English units, Imperial units, and United States customary units. ... This article is about the unit of length. ... A foot (plural: feet or foot;[1] symbol or abbreviation: ft or, sometimes, ′ – a prime) is a unit of length, in a number of different systems, including English units, Imperial units, and United States customary units. ...


The muscles and nerves in anemones are much simpler than those of other animals. Cells in the outer layer (epidermis) and the inner layer (gastrodermis) have microfilaments grouped together into contractile fibers. These are not true muscles because they are not freely suspended in the body cavity as they are in more developed animals. Since the anemone lacks a skeleton, the contractile cells pull against the gastrovascular cavity, which acts as a hydrostatic skeleton. The stability for this hydrostatic skeleton is caused by the anemone shutting its mouth, which keeps the gastrovascular cavity at a constant volume, making it more rigid.


Life cycle

Hundreds of anemones at low tide. They all are clones
Hundreds of anemones at low tide. They all are clones
Sea anemone in process of cloning
Sea anemone in process of cloning

Unlike other cnidarians, anemones (and other anthozoans) entirely lack the free-swimming medusa stage of the life cycle: the polyp produces eggs and sperm, and the fertilized egg develops into a planula that develops directly into another polyp. Image File history File links Metadata Size of this preview: 800 × 430 pixelsFull resolution (2168 × 1164 pixel, file size: 2. ... Image File history File links Metadata Size of this preview: 800 × 430 pixelsFull resolution (2168 × 1164 pixel, file size: 2. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Anthozoa is a class within the phylum Cnidaria that contains the sea anemones and corals. ... In biology, a medusa (also known as a hydromedusa) is a form of cnidarian in which the body is shortened on its principal axis and broadened, sometimes greatly, in contrast with the hydroid or polyp. ... Anatomy of a coral polyp. ... A planula is the free-swimming, flattened, ciliated, bilaterally symmetrical larva of a hydrozoan cnidarian. ...


A few anemones are parasitic to marine organisms. Anemones tend to stay in the same spot until conditions become unsuitable (prolonged dryness, for example), or a predator is attacking them. In the case of an attack, anemones can release themselves from the substrate and swim away to a new location using flexing motions.


The sexes in sea anemones are separate for some species while some are hermaphroditic. Both sexual and asexual reproduction may occur. In sexual reproduction males release sperm which stimulates females to release eggs, and fertilization occurs. The eggs or sperm are ejected through the mouth. The fertilized egg develops into a planula, which finally settles down and grows into a single anemone. They can also reproduce asexually by budding, binary fission, which involves pulling apart into two halves, and pedal laceration, in which small pieces of the pedal disc break off and regenerate into small anemones. A planula is the free-swimming, flattened, ciliated, bilaterally symmetrical larva of a hydrozoan cnidarian. ... High magnification view of a budding yeast Budding is the formation of a new organism by the protrusion of part of another organism. ... Binary fission Binary fission is the form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size, used by most prokaryotes. ... Definition A cut is an injury that results in a break or opening in the skin. ...


Ecology

Common (Ocellaris) clownfish (Amphiprion ocellaris) in their Magnificent sea anemone (Heteractis magnifica) home
Common (Ocellaris) clownfish (Amphiprion ocellaris) in their Magnificent sea anemone (Heteractis magnifica) home
Consuming a jellyfish.
Consuming a jellyfish.

The sea anemone has a foot which in most species attaches itself to rocks or anchors in the sand. Others also burrow into a stronger object. Some species attach to kelp and others are free-swimming. Although not plants and therefore incapable of photosynthesis themselves, many sea anemones form an important facultative symbiotic relationship with certain single-celled green algae species which reside in the animals' gastrodermal cells. These algae may be either zooxanthellae, zoochlorellae or both. The sea anemone benefits from the products of the algae's photosynthesis, namely oxygen and food in the form of glycerol, glucose and alanine; the algae in turn are assured a reliable exposure to sunlight and protection from micro-feeders, which the anemones actively maintain. The algae also benefit by being protected due to the presence of stinging cells called nematacysts, reducing the likelihood of being eaten by herbivores. Most species inhabit tropical reefs, although there are species adapted to relatively cold waters, intertidal reefs, and sand/kelp environments. Common Clownfish (Amphiprion ocellaris) in their Magnificent Sea Anemone (Heteractis magnifica) home. ... Common Clownfish (Amphiprion ocellaris) in their Magnificent Sea Anemone (Heteractis magnifica) home. ... Species See text. ... Binomial name Heteractis magnifica (Quoy & Gaimard, 1833) Heteractis magnifica (known variously as magnificent sea anemone or Ritteri anemone) is a species of sea anemone that lives in the Indo-Pacific area, and can grow up to 1 metre (3 feet) in diameter in the wild. ... Image File history File links Size of this preview: 800 × 600 pixelsFull resolution (1632 × 1224 pixel, file size: 1,006 KB, MIME type: image/jpeg) Sea Anemone is in process of consuming a jellyfish. ... Image File history File links Size of this preview: 800 × 600 pixelsFull resolution (1632 × 1224 pixel, file size: 1,006 KB, MIME type: image/jpeg) Sea Anemone is in process of consuming a jellyfish. ... For other uses, see Plant (disambiguation). ... The leaf is the primary site of photosynthesis in plants. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... Algae have conventionally been regarded as simple plants within the study of botany. ... Zooxanthellae are golden-brown intracellular endosymbionts of various marine animals and protozoa, especially anthozoans. ... Zoochlorella (plural zoochlorellae) is any single green algae that lives symbiotically within the body of many freshwater invertebrates and protozoans. ... General Name, symbol, number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, period, block 16, 2, p Appearance colorless (gas) pale blue (liquid) Standard atomic weight 15. ... Glycerine, Glycerin redirects here. ... Glucose (Glc), a monosaccharide (or simple sugar), is an important carbohydrate in biology. ... Alanine (Ala, A) also 2-aminopropanoic acid is a non-essential α-amino acid. ...

A porcelain crab living with an anemone, probably Entamacea quadricolor
A porcelain crab living with an anemone, probably Entamacea quadricolor

Image File history File linksMetadata Download high-resolution version (3008x2000, 2212 KB) Photograph of a porcelain crab living in a sea anomene, in Papua New Guinea. ... Image File history File linksMetadata Download high-resolution version (3008x2000, 2212 KB) Photograph of a porcelain crab living in a sea anomene, in Papua New Guinea. ... Genera Aliaporcellana Capilliporcellana Clastotoechus Euceramus Enosteoides Eulenaios Lissoporcellana Megalobrachuium Minyocerus Neopetrolisthes Neopisoma Pachycheles Parapetrolisthes Petrolisthes Pisidia Polyonyx Porcellana Porcellanella Pseudoporcellanella Raphidopus Ulloaia Porcelain crabs are decapod crustaceans in the family Porcellanidae, which superficially resemble true crabs. ...

Conservation

Marine aquarists with reef aquariums often seek to acquire anemone and clownfish for their home aquarium. To fulfill the demand, suppliers harvest anemones directly from coral reefs. Anemones reproduce extremely slowly, and are unlikely to replenish themselves in the regions where they have been over-harvested. Their removal can also negatively impact any creatures which share a symbiotic relationship with it, such as clownfish, anemone shrimp, and anemone crabs. For those aquarists who simply desire clownfish, it should be noted that clownfish can live in captivity without anemones. [2] Image File history File links Broom_icon. ...


Fossil record

Most Actiniaria do not form hard parts that can be recognized as fossils but a few fossils do exist; Mackenzia, from the Middle Cambrian Burgess Shale of Canada, is the oldest fossil identified as a sea anemone. The Middle Cambrian is an geological epoch that is part of the Cambrian Era. ... Hallucigenia sparsa, one of the organisms unique to the Burgess Shale. ...


Gallery

Image File history File links Metadata Size of this preview: 800 × 600 pixelsFull resolution (3072 × 2304 pixel, file size: 4. ...

References

  1. ^ Campbell N. & J. Reece (2002). Biology, 6th ed, San Francisco: Pearson Education. 
  2. ^ Shimek, R. (2004), p. 83. Marine Invertebrates. T.F.H. Publications, Inc. Neptune City, NJ.

Pearson Education is one of leading publishers of educational textbooks and other educational material, such as multimedia learning tools. ...

External links

Wikispecies has information related to:
Wikimedia Commons has media related to:
Actiniaria
  • Order Actiniaria
  • Actiniaria.com
  • Photos of various species of Sea Anemones from the Indopacific
  • Anemone Armies Battle to a Standoff
  • Anemone Wars: Clone armies deploy scouts, attack tidally - unsuspected military tactics
  • Sea anemones look like sea flowers but they are animals of the Phylum Cnidaria

  Results from FactBites:
 
Sea Anemone, Sea Anemone Information (266 words)
The tentacles protect the anemone and catch its food; they are studded with microscopic stinging capsules.
Sea Anemones are usually about 1 to 4 inches (2.5-10 cm) across, but a few grow to be 6 feet (1.8 m) across.
Reproduction : Sea Anemones reproduce by lateral fission (in which an identical animal sprouts out of the anemone's side) and by sexual reproduction (in which anemones release eggs and sperm, producing free-swimming larvae).
Sea Anemone - MSN Encarta (248 words)
Sea Anemone, common name for various marine, flower-like polyps having a cylindrical, or vase-like, body.
Most sea anemones reproduce sexually; budding and fission are comparatively rare.
The eggs are usually fertilized in the gastric cavity, and the young are discharged from the mouth as free-swimming larvae, which soon attach themselves to surfaces.
  More results at FactBites »

 
 

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