Giant Plumose Anemone Genus: Metridium Species: farcimen ITIS: 611773 Primary Common Name: Giant plumed anemone Common names (s): Plumose anemone, Metridium Synonymous name(s): Metridium giganteum Similar Species: Metridium senile (Metridium dianthus) General grouping: (pull down on site) Corals and anemones Geographic Range Range description: The Plumose anemone ranges from Alaska to southern California and along both sides of North America. Brief range description: (this should always be included in above description) Alaska to southern California Habitats (pull down on site) Habitat notes: M. farcimen can be found in both subtidal and low intertidal zones, including jetties, wharfs, harbours, breakwaters and floats. When found on wharfs, anemone communities of dense distribution are common. Larger specimens are often found solitarily in the subtidal. Found on pilings and docks in bays and on rocks and shells on the outer coast, down to a few hundred meters depth. Abundance Relative abundance: In a study of species abundance in Alaska, M. farcimen was the most commonly observed macro-invertebrate species and typically occurred on boulders, high-relief rock, and rock pavement, often in association with Primnoa spp. Species Description: The Giant plumose anemone, Metridium farcimen, is typically large, solitary, and subtidal. Oral disk is lobed and covered with short tentacles that may number in the hundreds; commonly white, uncommonly salmon, brown, or speckled. The species name farcimen, refers to its sausage-like appearance, as “farcimen” means; with stuffing or sausage. Subtidal animals can often reach 25cm in crown diameter and 50cm in height. However larger specimens have been reported up to a meter in height. Shape of the column is much longer than wide. Tentacles lining the mouth of the oral disk are quite fine, very numerous, slender and short. Tentacle coloration is typically transparent when the tentacles are expanded and take the color of the column when contracted. Distinctive features: Anemones are rich in nematocysts (stinging cells) which are used in both defense and attack. The normal tentacles contain these cells used for both defense and feeding. However, in large colonies of Plumose Anemones the species bordering the colony develop a different type of tentacle; "catch" tentacles. These tentacles, which are used to repel non-cloned anemones, take about 9 weeks to develop close to the mouth and may number as great as 19 on an individual organism. If the "catch" tentacles, which contain a different type of nematocysts, touch another anenome from a separate colony a stinging tip breaks of and releases the separate complement of nematocysts. This technique is used to repel intruding anemones. Interestingly, these tentacles can expand to a possible length of 12cm. Key Feature Large to one meter tall with lobed oral disc fringed with short fine tentacles; usually white but may be pinkish or tan-brown. Size: Height: up to 1 m (40 in.) Crown diameter: up to 25 cm (10 in.) Natural History General natural history: The animals generally appear motionless, but time-lapse movies show slow rhythms of expansion and contraction. The body can assume a wide variety of shapes. As in other anemones, the fluid in the gut, under positive pressure from the muscles of the body wall, act as a hydraulic skeleton, providing internal support. Additional support, along with elasticity and extensibility, is provided by the mesoglea or middle of the body wall, which contains an amorphous polymer network of collagen. An anemone crawls slowly along the substratum by muscular waves at its base. This distinctive large, solitary, subtidal species that lives on pilings in bays and on rocks and shells off the coast was once considered to be an ecotype of M. senile. Unlike regular feeding tentacles, catch tentacles have a complement of nematocysts, and as many as 19 may be present in a single anemone. These tentacles are capable of great expansion, and can stretch over 12 cm to explore their surroundings, extending and retracting rhythmically. But the catch tentacles don’t respond to food or clonemates, but if even a regular feeding tentacle of metridium makes contact with another anemone or non-clonemate, it sticks and stings and the stinging tips break off. The attacked individual may contract, bend, or move away, and after some time, tissue damage can be seen at the site of the clinging tentacle tip. Anemones in the center of a clone usually bear no catch tentacles, as these develop in a period of about 9 weeks if moved out to the border of the clone, or otherwise placed in contact with non clonemates. When a border metridium armed with catch tentacles encounters a green anemone, it may lash it repeatedly, causing it to contract or move away. The catch tentacles are clearly used for aggression against non clonemates and anemones of other species. Plumose Anemone symbiosis is an area in which little research has been done. Possible commensal behaviour may be similar to other anemones which have certain fish (e.g Clown Fish) which use the anemone. Related to corals and jellyfish, metridium anemones are part of the Phylum Cnidaria. They all have in common a feeding method that uses specialized stinging cells in their tentacles to stun and capture their prey. Scientists believe that metridium’s broad plumes form current eddies that aid in their feeding. Predator(s): The Plumose Anemone has few predators. Nudibranchs feed on small anenomes, while in Puget Sound (Washington State) a sea star Dermasterias imbricata has been found to feed on larger anemones. Prey: Both the small and large anemones feed primarily on zooplankton, using their stinging tentacles to catch the prey. The feeding appears non-selective. Scraps of fish, squid and small benthic (subtidal) organisms are also taken. Feeding behavior notes These sea anemones are sit-and-wait predators, voracious ones at that if you are living in the plankton. They all have in common a feeding method that uses specialized stinging cells in their tentacles to stun and capture their prey. Scientists believe that metridium’s broad plumes form currents and eddies that aid in their feeding. Reproduction The anemone reproduces both asexually and sexually. Asexual reproduction occurs as the anemone moves about, leaving small sections of its pedal disk (base) behind, in a process described as pedal laceration. Dense colonies can be formed in this manner, with the pedal disks forming small cloned rounded anemones that feed and grow. Sexual reproduction occurs in a broadcast spawning process whereby the males release sperm with wedged-shaped heads stimulating the females to release their eggs, about 0.1mm in diameter with a pinkish colouration. External fertilization occurs, with the zygote dividing to form a planula larva which swims in planktonic form. Planulae settle and metamorphose into young anemones Conservation Issues M. farcimen cannot survive where there is industrial pollution, sewage, sludge, or anoxic conditions, although they may tolerate high levels of pollution from boats and harbors. M. farcimen provides habitat for several commercially important groundfishes and have been identified as habitat areas of particular concern by the North Pacific Fishery Management Council.
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