Metridium senile

Researched By	Dr Keith Hiscock & Emily Wilson	Data Supplied By	MarLIN
Refereed by	This information is not refereed.
Taxonomy
Scientific name	Metridium senile	Common name	Plumose anemone
MCS Code	D710	Recent Synonyms	None
Phylum	Cnidaria	Subphylum
Superclass	Anthozoa	Class	Hexacorallia
Subclass		Order	Actiniaria
Suborder	Nynantheae	Family	Metridiidae
Genus	Metridium	Species	senile
Subspecies
Additional Information	Manuel (1988) describes two distinctive varieties. Var. dianthus is large with a tall column when expanded. The disc is deeply waved or folded. The many tentacles give a 'fluffy' appearance. Individuals may be 30 cm in height, with a basal diamer and tentacle span of 15 cm or more. Var. pallidus is a small form not exceeding 2.5 cm across the base with a flat disc without folds. Bucklin (1985) investigated biochemical genetic variation and concluded the presence of two morphs of Metridium senile but that they were variants resulting from different environmental conditions and were not taxonomically distinct and therefore not 'varieties' as described in many texts.
Taxonomy References	Howson & Picton, 1997, Hayward & Ryland, 1995b, Manuel, 1988, Bucklin, 1985
General Biology
Growth form	Radial, Globose	Feeding method	Passive suspension feeder
Mobility/Movement	Temporary attachment	Environmental position	Epilithic, Epifaunal
Typical food types	Zooplankton but also larger prey. (See additional information.)	Habit	Erect
Bioturbator	Not relevant	Flexibility	High (>45 degrees)
Fragility	Intermediate	Size	Medium-large(21-50cm)
Height	Up to 30 cm	Growth Rate	9 cm/month
Adult dispersal potential	<10m	Dependency	Independent
Sociability	Gregarious
Toxic/Poisonous?	No
Additional Information	Growth rate Bucklin (1987a) observed that Metridium senile grew rapidly in laboratory culture when fed daily reaching a mean pedal diameter of 45 cm after 5 months. Feeding Anthony (1997) noted that small anemones had the highest feeding efficiency at moderate to high flow regimes (which might help to account for the prevalence of small individuals at wave-exposed locations). Robbins & Schick (1980) found that current strength was the principal cause of expansion in Metridium senile rather than food availability. The greatest percentage of the anemones were expanded when the tide was running than at slack water. Examination of waste pellets of Metridium senile on wharf pilings in Monterey Bay, California (Purcell, 1976) revealed a diet of copepods, polychaete larvae, bivalve and gastropod veligers, copepod naupliii, and barnacle nauplii and cyprids. Sebens (1984) demonstrated that barnacle cyprids, ascidian larvae and gammarid amphipods were the preferred food of Metridium senile over invertebrate eggs, foramaniferans, calanoid and harpacticoid copepods and ostracods. Predation on Metridium senile Metridium senile is subject to predation from both small and large consumers. The life stages of the sea spider Pycnogonum littorale found feeding on the anemone were reported by Wilhelm et al. (1997). The sea slug Aeolidia papillosa also feeds on Metridium senile (see, for instance, Reidy, 1996; Sebens, 1985). Sebens (1985) reported heavy mortality every winter in the Gulf of Maine, USA from Aeolidia papillosa. However, infestations may be sporadic. Gorzula & Cameron (1976) reported a population boom of Aeolidia papillosa at Millport, Firth of Clyde during February 1974 and that it was the third recorded that century. Effects on the Metridium senile population were considerable although the slugs vanished after four weeks. Epitonid snails (wentletraps) feed on anemones and Perron (1978) observed that Metridium senile was the preferred prey of Epitonium greenlandicum in the Bay of Fundy. Whether north-east Atlantic wentletraps feed on Metridium senile is uncertain although Graham (1988) notes that Epitonium clathrus feeds on Anemonia sulcata. Larger species that eat whole anemones include the black bream Spondyliosoma cantharus (Mattacola, 1976) and, in Newfoundland, the winter flounder Pseudopleuronectes americanus (Keats, 1990).
Biology References	Anthony, 1997, Reidy, 1996, Wilhelm et al., 1997, Keats, 1990, Bucklin, 1987a, Mattacola, 1976, Gorzula & Cameron, 1976, Perron, 1978, Graham, 1988
Distribution and Habitat
Distribution in Britain & Ireland	All British and Irish coasts.
Global distribution	See additional information below.
Biogeographic range	Not researched	Depth range	Lower shore to considerable depths.
Migratory	Non-migratory / Resident
Distribution Additional Information	The species occurs from Biscay to Scandinavia in the northeast Atlantic. It is unknown from the western basin of the Mediterranean but recorded from the Adriatic (where it is believed to have been introduced) (Manual 1988). The same species occurs on the west and east coasts of North America. It has recently (Griffiths et al., 1996) been reported from Table Bay Harbour in South Africa where it was probably introduced from Europe. Both dianthus and pallidum forms may occur in estuaries and pallidum in brackish creeks. Braber & Borghouts (1977) recorded Metridium senile from salinities as low as 10ppt Chlorinity (about 19psu) in the Delta Region of the Netherlands.
Substratum preferences	Bedrock, Large to very large boulders, Biogenic reef, Artificial (e.g. metal/wood/concrete), Caves, Overhangs	Physiographic preferences	Offshore seabed, Strait / sound, Ria / Voe
Biological zone	Sublittoral Fringe, Upper Infralittoral, Lower Infralittoral, Upper Circalittoral, Lower Circalittoral	Wave exposure	Extremely Exposed, Very Exposed, Exposed, Moderately Exposed, Sheltered, Very Sheltered, Extremely Sheltered
Tidal stream strength/Water flow	Very Strong (>6 kn), Strong (3-6 kn), Moderately Strong (1-3 kn)	Salinity	Full (30-40 psu)
Habitat Additional Information
Distribution References	Hayward & Ryland, 1995b, Manuel, 1988, Griffiths et al., 1996, Braber & Borghouts, 1977
Reproduction/Life History
Reproductive type	Fission, Gonochoristic	Developmental mechanism	Lecithotrophic
Reproductive Season	August to September	Reproductive Location	Water column
Reproductive frequency	Insufficient information	Regeneration potential	No
Life span	11-20 years	Age at reproductive maturity	Insufficient information
Generation time	Insufficient information	Fecundity	Insufficient information
Egg/propagule size	Insufficient information	Fertilization type	External
Larvae/Juveniles Larval/Juvenile dispersal potential >10km Larval settlement period Insufficient information Duration of larval stage 1-6 months
Additional Information	The Plymouth Marine Fauna (Marine Biological Association, 1957) reports that ova and sperm are produced in August and September at Plymouth. Bull (1939b) records that ova and sperm are given off at intervals throughout the year in north-east England. An account of reproductive cycles in Californian Metridium senile, where spawning occurred in September and October, is given in Bucklin (1982). Sebens (1985) suggests that the larva is lecithotrophic but has a 'pre-metamorphosis' period of months, a dispersal potential of >10,000m and a colonization rate of 5-10 years. Metridium senile colonizes areas aggressively. In studies of succession in rock wall communities in the Gulf of Maine, USA, Sebens (1985), the anemone was a late colonizer but grew over earlier colonizers and used specialized 'catch-tentacles' to damage other anemones and soft corals. The presence of such 'catch-tentacles' is also reported for Metridium senile in Britain (Williamson, 1975). Growth is rapid. Bucklin (1985), working in Britain, found that for Metridium senile f. dianthus fragments and for Metridium senile f. pallidum newly settled individuals, a growth rate of up to 0.6 mm and 0.8 mm in pedal diameter per day occurred respectively. Bucklin (1987a) found that, for Metridium senile from California, individuals showed rapid growth to large sizes when fed at frequent intervals. Mean size grew steadily during the first eight months then levelled off. An increase from 5 cm² pedal disk area to 45 cm² occurred within 12 months. No information on longevity has been found although it would be expected that individuals are long-lived (10 years +).
Reproduction References	MBA, 1957, Bull, 1939b, Bucklin, 1982, Williams, 1975, Bucklin, 1985, Bucklin, 1987b