''Metridium farcimen'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

sea anemone Sea anemones ( ) are a group of predation, predatory marine invertebrates constituting the order (biology), order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemone ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Metridiidae. It is commonly known as the giant plumose anemone or white-plumed anemone. It is found in the eastern Pacific Ocean from Alaska down to Catalina Island, California.

Taxonomy

In 1990, Fautin et al. examined the validity of the name ''Metridium giganteum''. A further study in 2000 concluded that ''Actinia priapus''; Tilesius, 1809, ''Actinia farcimen''; Brandt, 1835, and ''Isometridium rickettsi''; Carlgren, 1949 were all

synonym A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

s of ''Metridium giganteum''. Of these, ''Actinia farcimen'' was the name first published. It is, however, a junior

homonym In linguistics, homonyms are words which are either; '' homographs''—words that mean different things, but have the same spelling (regardless of pronunciation), or '' homophones''—words that mean different things, but have the same pronunciat ...

so the valid name for the species is ''Metridium farcimen''; (Brandt, 1835).

Description

''Metridium farcimen'' is a large sea anemone, occasionally reaching a height of one metre (39 in) when fully extended. More usually it is or less in height but is very variable in shape. It can retract its tentacles and form a ball up to in diameter. The column is slender, smooth and studded with acontia. These are openings through which thread-like

nematocyst A cnidocyte (also known as a cnidoblast) is a type of cell containing a large secretory organelle called a ''cnidocyst'', that can deliver a sting to other organisms as a way to capture prey and defend against predators. A cnidocyte explosively ...

s from inside the body wall can protrude. There are no tubercles and the column is topped by a parapet. The oral disc is lobed and deeply convoluted at the edge and bears well over 100 fine, short, tapering tentacles. The colour is generally opaque white, but orange, salmon and brown specimens sometimes occur. Large specimens have been seen to have long, thick, fighting tentacles, used to drive away other anemones trying to settle too close.''Metridium farcimen'' (Brandt, 1835)
Actiniaria.com. Retrieved 2011-11-24. Some individuals on the edge of large colonies have several of these fighting tentacles on their lips, which they use to repel non-clonal anemones.
Race Rocks. Retrieved 2011-11-24. These

colonies A colony is a territory subject to a form of foreign rule, which rules the territory and its indigenous peoples separated from the foreign rulers, the colonizer, and their '' metropole'' (or "mother country"). This separated rule was often or ...

emanate from one individual through

cloning Cloning is the process of producing individual organisms with identical genomes, either by natural or artificial means. In nature, some organisms produce clones through asexual reproduction; this reproduction of an organism by itself without ...

. ''Metridium farcimen'' might be confused with '' Metridium dianthus'' which occupies the same habitat and has a similar colour and form, but that species seldom exceeds in height, has fewer than 100 tentacles and has an unlobed oral disc.

Distribution

''Metridium farcimen'' is found on the western seaboard of the United States and Canada. Its range extends from

Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...

southwards to

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

. It is at its most common in

Puget Sound Puget Sound ( ; ) is a complex estuary, estuarine system of interconnected Marine habitat, marine waterways and basins located on the northwest coast of the U.S. state of Washington (state), Washington. As a part of the Salish Sea, the sound ...

and around

Vancouver Island Vancouver Island is an island in the northeastern Pacific Ocean and part of the Canadian province of British Columbia. The island is in length, in width at its widest point, and in total area, while are of land. The island is the largest ...

. It is found in the

sublittoral zone The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth. From the point of view of marine biology it forms a relatively stable and well-illuminated ...

on rocks,

mollusc shell The mollusc (or mollusk) shell is typically a calcareous exoskeleton which encloses, supports and protects the soft parts of an animal in the phylum Mollusca, which includes snails, clams, tusk shells, and several other classes. Not all shelled ...

s, pilings, docks and other man-made structures and even in polluted waters. It is also found at great depths, near

hydrothermal vent Hydrothermal vents are fissures on the seabed from which geothermally heated water discharges. They are commonly found near volcanically active places, areas where tectonic plates are moving apart at mid-ocean ridges, ocean basins, and hot ...

s, cold water seeps and decomposing whale carcasses on the

seabed The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as seabeds. The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...

Biology

''Metridium farcimen'' is a

carnivore A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they ar ...

. It captures small invertebrates,

zooplankton Zooplankton are the heterotrophic component of the planktonic community (the " zoo-" prefix comes from ), having to consume other organisms to thrive. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequent ...

and other food particles with the nematocysts on its tentacles and thrusts them into the mouth in the centre of its oral disc. A study released in June 2021 found that these large anemones consume land-dwelling insects and ostracods. Large anemones have few predators but smaller specimens are eaten by the sea stars, '' Pisaster spp.'', and by various

nudibranch Nudibranchs () are a group of soft-bodied marine gastropod molluscs, belonging to the order Nudibranchia, that shed their shells after their larval stage. They are noted for their often extraordinary colours and striking forms, and they have b ...

s. The starfish, '' Dermasterias imbricata'', has been observed feeding on larger anemones in Puget Sound.''Metridium giganteum''
Evergreen Natural History Database. Retrieved 2011-11-24. Reproduction takes place with the liberation of eggs and sperm from the gonads embedded in the body wall which are then ejected through the mouth. Fertilised eggs develop into

planula A planula is the free-swimming, flattened, ciliated, bilaterally symmetric larval form of various cnidarian species and also in some species of Ctenophores, which are not related to cnidarians at all. Some groups of Nemerteans also produce larva ...

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e. After several moults, these settle and

metamorphose Metamorphosis is a biological process by which an animal physically developmental biology, develops including birth, birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through ...

into polyps. ''Metridium farcimen'' occurs as solitary individuals or as congregations of genetically distinct individuals and does not replicate asexually (Bucklin, 1987a). Individuals can live for many years.

References

{{Taxonbar, from=Q2300011 Metridiidae Animals described in 1809