Metridium senile
Encyclopedia
Metridium senile, common name
the plumose anemone or frilled anemone, is a species
of sea anemone
in the family
Metridiidae
. It is found in the seas off northwest Europe and the east and west coasts of North America.
. The column is long, smooth and cylindrical, of a fleshy consistency with a slimy surface lubricated with mucus
. There are no warts or suckers and the column is topped by a parapet and deep groove. The oral disc is broad and deeply lobed into several curving sections that overhang the column. The slender, pointed tentacle
s are very numerous in larger specimens though fewer and relatively longer in smaller ones. Those near the margin are crowded and short whereas further into the disc they are longer and more dispersed. The colour range of this sea anemone is large but for any one specimen the colour is uniform throughout, except for the orange-red lip surrounding the central mouth. Colours include, white, cream, pink, orange, red, grey, brown and olive-green. The tentacles are translucent but may have a white band, and some specimens have a darker column and much paler disc.
There are several distinct forms and various intermediate ones. M. senile var. dianthus is described above. It has over 1000 tentacles and exhibits a feathery appearance. It can grow to 30 cm (12 in) tall with a base diameter of 15 cm (6 in) and a similar tentacle span. M. senile var. pallidus is much smaller, seldom exceeding 2.5 cm (0.984251968503937 in) base diameter, and has a much less convoluted disc with fewer than 200 tentacles. It seems to be a dwarf race, becoming sexually mature while still small. There are also a number of intermediate forms.
Johannes Peter Müller
has described the variety dianthus as "the most beautiful of all the anemones". It is indeed an impressive sight with the tentacles fully expanded, resembling a palm tree
, but when retracted it can become a low, irregularly shaped, jelly-like disc of unattractive appearance. When exposed to the air by a retreating tide, it does not always retract but may hang under an overhang in a limp fashion looking like a wet glove with a single drop of water dangling at its tip.
north to Norway and Iceland. It also occurs on the east and west coasts of North America and has arrived in South African waters. It is found on the lower shore and the neritic zone
at depths down to about 100 m (328 ft).
s and scallop
s. One oyster was found to have twenty anemones crowded onto its shell.
and catches small organisms floating past in the current. Its diet largely consists of copepod
s, worm larvae, mollusc
larvae, ascidia
n larvae, amphipods and barnacle
larvae. There are reports of the sea anemone itself being eaten by the sea slug
Aeolidia papillosa
("shag rug nudibranch"), the sea spider
, Pycnogonum littorale, wentletrap
sea snails Epitonium
spp., the flounder, Pseudopleuronectes americanus and the black bream, Spondyliosoma cantharus.
M. senile is a protandric hermaphrodite – it starts life as one sex and changes to the other when it is older. Eggs
or sperm
develop in the gonad
s embedded in the mesentery
that lines the coelom
. They are ejected through the mouth, and when fertilised develop into planula
larva
e. After one to six months drifting in the plankton
, these settle and metamorphose
into juveniles. By this means the plume anemone can spread to new areas some way from its origins.
The plume anemone can also increase its numbers by asexual reproduction
. An individual can undergo binary fission
by splitting in half and growing into two organisms. Or it can develop buds
which grow into new individuals before becoming detached. Fragmentation, also known as basal laceration, is another mechanism by which the number of individuals can be increased rapidly. In an aquarium
, the anemone can sometimes be seen to glide across a hard surface such as the glass wall, leaving fragments behind in the process. After a week or more, each piece can be seen to be developing a disc and tentacles and in due course grows into a new individual.
In 1856, in Torbay
, England, a waterlogged board was brought to the surface by a dredger. It was found to have over 400 individuals of M. senile of varying sizes living on it. Those on one side were all white while the other side housed only individuals that were orange. The naturalist
Philip Henry Gosse
, writing about this, surmised that each side housed individuals resulting from the fragmentation of a single original individual that had settled on the board.
The growth rate of this species is rapid. Juveniles have been found to increase the diameter of their bases by 0.6 to 0.8 mm per day. By the age of 5 months, they have been found to reach an average basal diameter of 45 mm (2 in).
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
the plumose anemone or frilled anemone, is a species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of sea anemone
Sea anemone
Sea anemones are a group of water-dwelling, predatory animals of the order Actiniaria; they are named after the anemone, a terrestrial flower. Sea anemones are classified in the phylum Cnidaria, class Anthozoa, subclass Zoantharia. Anthozoa often have large polyps that allow for digestion of larger...
in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Metridiidae
Metridiidae
Metridiidae is a family of sea anemones in the order Actiniaria.-Characteristics:Members of the family Metridiidae are characterised by having a mesogloeal sphincter muscle and by the mesenterial arrangement, with the mesenteries not being divided into macronemes and microcnemes...
. It is found in the seas off northwest Europe and the east and west coasts of North America.
Description
The base of Metridium senile is considerably wider than the column and is attached to rock or another substrateSubstrate
Substrate may mean:*Substrate , Natural stone, masonry surface, ceramic and porcelain tiles*Substrate , the material used in the bottom of an aquarium*Substrate , the material used in the bottom of a vivarium or terrarium...
. The column is long, smooth and cylindrical, of a fleshy consistency with a slimy surface lubricated with mucus
Mucus
In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...
. There are no warts or suckers and the column is topped by a parapet and deep groove. The oral disc is broad and deeply lobed into several curving sections that overhang the column. The slender, pointed tentacle
Tentacle
A tentacle or bothrium is one of usually two or more elongated flexible organs present in animals, especially invertebrates. The term may also refer to the hairs of the leaves of some insectivorous plants. Usually, tentacles are used for feeding, feeling and grasping. Anatomically, they work like...
s are very numerous in larger specimens though fewer and relatively longer in smaller ones. Those near the margin are crowded and short whereas further into the disc they are longer and more dispersed. The colour range of this sea anemone is large but for any one specimen the colour is uniform throughout, except for the orange-red lip surrounding the central mouth. Colours include, white, cream, pink, orange, red, grey, brown and olive-green. The tentacles are translucent but may have a white band, and some specimens have a darker column and much paler disc.
There are several distinct forms and various intermediate ones. M. senile var. dianthus is described above. It has over 1000 tentacles and exhibits a feathery appearance. It can grow to 30 cm (12 in) tall with a base diameter of 15 cm (6 in) and a similar tentacle span. M. senile var. pallidus is much smaller, seldom exceeding 2.5 cm (0.984251968503937 in) base diameter, and has a much less convoluted disc with fewer than 200 tentacles. It seems to be a dwarf race, becoming sexually mature while still small. There are also a number of intermediate forms.
Johannes Peter Müller
Johannes Peter Müller
Johannes Peter Müller , was a German physiologist, comparative anatomist, and ichthyologist not only known for his discoveries but also for his ability to synthesize knowledge.-Early years and education:...
has described the variety dianthus as "the most beautiful of all the anemones". It is indeed an impressive sight with the tentacles fully expanded, resembling a palm tree
Arecaceae
Arecaceae or Palmae , are a family of flowering plants, the only family in the monocot order Arecales. There are roughly 202 currently known genera with around 2600 species, most of which are restricted to tropical, subtropical, and warm temperate climates...
, but when retracted it can become a low, irregularly shaped, jelly-like disc of unattractive appearance. When exposed to the air by a retreating tide, it does not always retract but may hang under an overhang in a limp fashion looking like a wet glove with a single drop of water dangling at its tip.
Distribution
M. senile is found on the northwest coasts of Europe from the Bay of BiscayBay of Biscay
The Bay of Biscay is a gulf of the northeast Atlantic Ocean located south of the Celtic Sea. It lies along the western coast of France from Brest south to the Spanish border, and the northern coast of Spain west to Cape Ortegal, and is named in English after the province of Biscay, in the Spanish...
north to Norway and Iceland. It also occurs on the east and west coasts of North America and has arrived in South African waters. It is found on the lower shore and the neritic zone
Neritic zone
The neritic zone, also called coastal waters, the coastal ocean or the sublittoral zone, is the part of the ocean extending from the low tide mark to the edge of the continental shelf, with a relatively shallow depth extending to about 200 meters...
at depths down to about 100 m (328 ft).
Habitat
M. senile adheres to rocks, boulders, man-made structures, pebbles and shells. It favours places where the current is strong. Smaller forms inhabit the lower shore where they are found under stones, beneath overhangs and in shaded places. It specially favours soft rocks, honeycombed by molluscs, and the underside of large boulders. At greater depths, the larger forms are sometimes abundant on pilings, submerged pipes, pier supports and harbour walls. In the English Channel the anemones are often brought up when trawling in shallow waters for oysterOyster
The word oyster is used as a common name for a number of distinct groups of bivalve molluscs which live in marine or brackish habitats. The valves are highly calcified....
s and scallop
Scallop
A scallop is a marine bivalve mollusk of the family Pectinidae. Scallops are a cosmopolitan family, found in all of the world's oceans. Many scallops are highly prized as a food source...
s. One oyster was found to have twenty anemones crowded onto its shell.
Biology
M. senile is a predatorPredation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
and catches small organisms floating past in the current. Its diet largely consists of copepod
Copepod
Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...
s, worm larvae, mollusc
Mollusca
The Mollusca , common name molluscs or mollusksSpelled mollusks in the USA, see reasons given in Rosenberg's ; for the spelling mollusc see the reasons given by , is a large phylum of invertebrate animals. There are around 85,000 recognized extant species of molluscs. Mollusca is the largest...
larvae, ascidia
Ascidia
Ascidia is a genus of tunicates in the family Ascidiidae.-Selected species:* Ascidia archaia Sluiter, 1890* Ascidia bocatorensis Bonnet & Rocha, 2011* Ascidia collini Bonnet & Rocha, 2011* Ascidia corallicola Bonnet & Rocha, 2011...
n larvae, amphipods and barnacle
Barnacle
A barnacle is a type of arthropod belonging to infraclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile suspension feeders, and have...
larvae. There are reports of the sea anemone itself being eaten by the sea slug
Sea slug
Sea slug is a common name used for several different groups of saltwater snails that either lack a shell or have only an internal shell, in other words this name is used for various lineages of marine gastropod mollusks that are either not conchiferous or appear not to be.The phrase "sea slug" is...
Aeolidia papillosa
Aeolidia papillosa
Aeolidia papillosa is a species of sea slug, an aeolid nudibranch, a marine gastropod mollusk in the family Aeolidiidae. A. papillosa has many common names including the shaggy mouse nudibranch or the shag rug nudibranch, in part due to its shape and its numerous flattened cerata that make it look...
("shag rug nudibranch"), the sea spider
Sea spider
Sea spiders, also called Pantopoda or pycnogonids, are marine arthropods of class Pycnogonida. They are cosmopolitan, found especially in the Mediterranean and Caribbean Seas, as well as the Arctic and Antarctic Oceans. There are over 1300 known species, ranging in size from to over in some deep...
, Pycnogonum littorale, wentletrap
Wentletrap
Wentletraps are small, often white, very high-spired, predatory or ectoparasitic sea snails, marine gastropod mollusks, in the family Epitoniidae.The word wentletrap originated in Dutch , and it means spiral staircase...
sea snails Epitonium
Epitonium
Epitonium is a genus of small predatory sea snails, marine gastropod mollusks. Epitonium is the type genus of the family Epitoniidae, the wentletraps....
spp., the flounder, Pseudopleuronectes americanus and the black bream, Spondyliosoma cantharus.
M. senile is a protandric hermaphrodite – it starts life as one sex and changes to the other when it is older. Eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
or sperm
Sperm
The term sperm is derived from the Greek word sperma and refers to the male reproductive cells. In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell...
develop in the gonad
Gonad
The gonad is the organ that makes gametes. The gonads in males are the testes and the gonads in females are the ovaries. The product, gametes, are haploid germ cells. For example, spermatozoon and egg cells are gametes...
s embedded in the mesentery
Mesentery
In anatomy, the mesentery is the double layer of peritoneum that suspends the jejunum and ileum from the posterior wall of the abdomen. Its meaning, however, is frequently extended to include double layers of peritoneum connecting various components of the abdominal cavity.-Mesentery :The...
that lines the coelom
Coelom
The coelom is a fluid-filled cavity formed within the mesoderm. Coeloms developed in triploblasts but were subsequently lost in several lineages. Loss of coelom is correlated with reduction in body size...
. They are ejected through the mouth, and when fertilised develop into planula
Planula
A planula is the free-swimming, flattened, ciliated, bilaterally symmetric larval form of various cnidarian species. The planula forms from the fertilized egg of a medusa, as the case in scyphozoans and some hydrozoans, or from a polyp, as in the case of anthozoans...
larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e. After one to six months drifting in the plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
, these settle and metamorphose
Metamorphosis
Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation...
into juveniles. By this means the plume anemone can spread to new areas some way from its origins.
The plume anemone can also increase its numbers by asexual reproduction
Asexual reproduction
Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. A more stringent definition is agamogenesis which is reproduction without...
. An individual can undergo binary fission
Fission (biology)
In biology, fission is the subdivision of a cell into two or more parts and the regeneration of those parts into separate cells...
by splitting in half and growing into two organisms. Or it can develop buds
Budding
Budding is a form of asexual reproduction in which a new organism grows on another one. The new organism remains attached as it grows, separating from the parent organism only when it is mature. Since the reproduction is asexual, the newly created organism is a clone and is genetically identical...
which grow into new individuals before becoming detached. Fragmentation, also known as basal laceration, is another mechanism by which the number of individuals can be increased rapidly. In an aquarium
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
, the anemone can sometimes be seen to glide across a hard surface such as the glass wall, leaving fragments behind in the process. After a week or more, each piece can be seen to be developing a disc and tentacles and in due course grows into a new individual.
In 1856, in Torbay
Torbay
Torbay is an east-facing bay and natural harbour, at the western most end of Lyme Bay in the south-west of England, situated roughly midway between the cities of Exeter and Plymouth. Part of the ceremonial county of Devon, Torbay was made a unitary authority on 1 April 1998...
, England, a waterlogged board was brought to the surface by a dredger. It was found to have over 400 individuals of M. senile of varying sizes living on it. Those on one side were all white while the other side housed only individuals that were orange. The naturalist
Natural history
Natural history is the scientific research of plants or animals, leaning more towards observational rather than experimental methods of study, and encompasses more research published in magazines than in academic journals. Grouped among the natural sciences, natural history is the systematic study...
Philip Henry Gosse
Philip Henry Gosse
Philip Henry Gosse was an English naturalist and popularizer of natural science, virtually the inventor of the seawater aquarium, and a painstaking innovator in the study of marine biology...
, writing about this, surmised that each side housed individuals resulting from the fragmentation of a single original individual that had settled on the board.
The growth rate of this species is rapid. Juveniles have been found to increase the diameter of their bases by 0.6 to 0.8 mm per day. By the age of 5 months, they have been found to reach an average basal diameter of 45 mm (2 in).