''Protanthea simplex'' 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 ...

found in deep water off the coasts of north west Europe. It is the only species in the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

genus ''Protanthea''.

Description

''P. simplex'' is a delicate sea anemone. The

tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

s are non-retractable and have a frosty appearance and are usually held outstretched. The column is salmon pink, flared below the tentacles and reaches lengths of up to two centimetres. It has a flattened, lightly adherent base bulging out below the pedal disc. There are up to 200 slender, translucent, white or pale pink tentacles up to one and a half centimetres long arranged in five rings. When the orangeish-pink gonads are ripe, they may be visible through the wall of the column.

Distribution

This species is found in both shallow and deep water around the western coast of Scotland from the

Firth of Clyde The Firth of Clyde, is the estuary of the River Clyde, on the west coast of Scotland. The Firth has some of the deepest coastal waters of the British Isles. The Firth is sheltered from the Atlantic Ocean by the Kintyre, Kintyre Peninsula. The ...

northward, particularly in sea lochs. It is also found round the coasts of the

Skagerrak The Skagerrak (; , , ) is a strait running between the North Jutlandic Island of Denmark, the east coast of Norway and the west coast of Sweden, connecting the North Sea and the Kattegat sea. The Skagerrak contains some of the busiest shipping ...

and northern

Kattegat The Kattegat (; ; ) is a sea area bounded by the peninsula of Jutland in the west, the Danish straits islands of Denmark and the Baltic Sea to the south and the Swedish provinces of Bohuslän, Västergötland, Halland and Scania in Swede ...

and in one location in

Connemara Connemara ( ; ) is a region on the Atlantic Ocean, Atlantic coast of western County Galway, in the west of Ireland. The area has a strong association with traditional Irish culture and contains much of the Connacht Irish-speaking Gaeltacht, ...

Galway Galway ( ; , ) is a City status in Ireland, city in (and the county town of) County Galway. It lies on the River Corrib between Lough Corrib and Galway Bay. It is the most populous settlement in the province of Connacht, the List of settleme ...

, Ireland. It seems to prefer vertical rock faces in sheltered sites with little movement of water and has been found as deep as five hundred metres.

Biology

This species is a passive

suspension feeder Filter feeders are aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a spec ...

. It is often solitary but it has been recorded at densities of up to two thousand per square metre. It shows an unusual behaviour when occasionally it loses

muscle tone In physiology, medicine, and anatomy, muscle tone (residual muscle tension or tonus) is the continuous and passive partial contraction of the muscles, or the muscle's resistance to passive stretch during resting state.O’Sullivan, S. B. (2007) ...

and hangs limply from its pedal disc attachment. At other times it is very active, exhibiting a violent thrashing of the tentacles in response to external stimuli. Reproduction can be by sexual or asexual means. In sexual reproduction, eggs and sperm are ejected through the mouth and liberated into the sea. The fertilised egg develops into a

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 ...

, which settles after fifteen to twenty days and grows into a new individual. In

asexual reproduction Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the f ...

, fragments of the column are capable of regenerating into new individuals.Manuel, R.L., (1988). British Anthozoa. London: Academic Press. Synopses of the British Fauna, no. 18.

References

External links

* {{Taxonbar, from1=Q21446708, from2=Q3331020 Gonactiniidae Hexacorallia genera Taxa described in 1891 Monotypic cnidarian genera