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Urticina piscivora or the fish-eating anemone
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Former name : Tealia piscivora
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| Phylum | Cnidaria |
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| Class | Anthozoa | |
| Order | Actiniara | |
| Family | Actiniidae | |
| Physical characteristics | deep red to maroon column, appearing velvety, tentacles are usually write, but occasionally are red | |
| Distribution | Northern Pacific, from Alaska to La Jolla, California | |
| Habitat | on sides of rocks from the low intertidal to about 48m | |
| Conservation Status | not protected according to redlist.org |
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The phylum Cnidaria includes anemones, corals, jellyfish, and hydras. Another name for Cnidarians is Coelenterata, which refers to the single body cavity. Sea anemones inhabit deep coastal waters throughout the world. They are often brightly colored and live commonly attached to rocks,shells or submerged timbers. The major part of the sea anemone body is formed by a heavy column, which may be smooth, or bear tubercles or even tentacle-like outgrowth. At the aboral end of the column there is a flattened pedal disc for attachment. The oral end bears eight to several hundred tentacles with nematocysts. In its centre is the slit-shaped mouth bearing a ciliated groove called siphonoglyph.
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Some Sea Anemones have a symbiotic relationship with algae named zooxanthellae. The algae are found within the gastrodermal cells of the Anemone, which uses the photosynthetic products from the zooxanthellae as their carbohydrates. The zooxanthellae use the nutrients of the Anemone that come out of the Anemone as waste. U. piscivora however does not form any kind of zooxanthellae. The sexes are generally separated in sea anemones, but some species may be serial hermaphodites. The typical reproductive pattern is to spawn into the water where fertilization occurs. Asexual reproduction occurs in some sea anemones: splitting by two, called binary fission; others will leave little piece of the pedal disk behind as they move, called pedal laceration. |
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This anemone has a deep red smooth column and there tentacles are usually white. Its tentacular crown is 20 cm in diameter. The structure of U. piscivora consists of a bag formed by three layers a non-cellular "mesoglea" between two tissues, an outer layer called "epidermis" and an internal called gastrodermis. The interior of the bag is the gastrovascular cavity. Its tentacles are heavily loaded with nematocysts to capture their prey. They are caught into a capsule by the epidermal cells and then by releasing a fluid filling cavity, immobilizing their prey. U. piscivora possess quite virulent stings sufficiently potent to cause long-lasting necrotic lesions on humans.
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U. piscivora eats small fish and invertebrates. One fish species, however, the Oxylebius pictus (painted greenling), has been observed lying unharmed in this anemone thus using the anemone as cover and defense. This coexistence is a mutualism comparable to the well known clownfish-sea anemone-mutalism (for example Amphiprion ocellaris on Heteractis spec. or, for the cineasts, the home of Nemo in Pixar's "Finding Nemo"). The fish keeps debris and parasites away from the anemone while the anemone offers cover and defence for the fish. Still the cohabitat is faculativ as O. pictus also lives in absence of U. piscivora. More information on these kinds of mutalism can be found here.
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http://www.racerocks.com/ |
| http://www.reefs.org/library/aquarium_net/0198/0198_3.html |
| Anemone fishes and their host sea amemones, Daphne G. Fautin, Gerald R. Allen |
| Guide to Marine Invertebrates, Alaska to Baja California, Daniel W. Gotshall, Sea Challengers.Monterey, California, 1994, p 26 |
| Invertebrate Zoology, Fifth edition, Robert D. Barnes, 1986, p 122 |