The snake pipefish (''Entelurus aequoreus'') is a species of pipefish, from the family Syngnathidae, native to the northeastern Atlantic Ocean where they are generally found amongst algae close in to shore. It is the largest species of pipefish recorded in European waters and has spread into arctic waters in the early 2000s.

Description

The snake pipefish has a very long, elongated and slender body which has a smooth skin and rounded cross-section and which is distinguished from other

sympatric In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species sh ...

pipefishes by the near lack of bony rings. It has a long head, with a thin dark stripe in its sides, with a long, concave snout and a very small, protractile mouth. The long based dorsal fin has 37-47 short rays while the caudal fin is minute and there are no pectoral fins or

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

s. They are pale brown or yellowish-green in colour with each of the 28-31 rings on the body marked out by pale blue rings with dark margins. The opening to the gills has been reduced to a pore in the membrane above the

opercle The operculum is a series of bones found in bony fish and chimaeras that serves as a facial support structure and a protective covering for the gills; it is also used for respiration and feeding. Anatomy The opercular series contains four bon ...

and the gill membranes are fused to the body and the isthmus. They can grow to total lengths of in males and in females, although they are more commonly around and respectively. The juveniles of less than 70 mm in length have membranous pectoral fins which disappear as they mature.

Distribution

The snake pipefish occurs in the north eastern Atlantic from Iceland and Norway to the Azores, into the Baltic Sea. In the early 2000s it expanded its range northwards as far as

Svalbard Svalbard ( , ), also known as Spitsbergen, or Spitzbergen, is a Norwegian archipelago in the Arctic Ocean. North of mainland Europe, it is about midway between the northern coast of Norway and the North Pole. The islands of the group range ...

and the Barents Sea. Abstract It is not found in the Mediterranean Sea.

Habitat and biology

The snake pipefish occurs in more open and deeper water than other species of pipefish, with a depth range of and it lives among kelp and other types of deep water sea weeds, as well as sea grass such as ''

Zostera marina ''Zostera marina'' is a flowering vascular plant species as one of many kinds of seagrass, with this species known primarily by the English name of eelgrass with seawrack much less used, and refers to the plant after breaking loose from the submer ...

'', but some individuals both young and large adults have been caught in pelagic waters. Its colour and patterning provides good camouflage in such habitats. The colonisation of the

Waddensee The Wadden Sea ( nl, Waddenzee ; german: Wattenmeer; nds, Wattensee or ; da, Vadehavet; fy, Waadsee, longname=yes; frr, di Heef) is an intertidal zone in the southeastern part of the North Sea. It lies between the coast of northwestern conti ...

sand flats by the invasive Japanese seaweed ''

Sargassum muticum ''Sargassum muticum'', commonly known as Japanese wireweed, is a large brown seaweed of the genus ''Sargassum''. It is an invasive seaweed with high growth rate (up to 10 cm per day during spring). It has an efficient dispersion thanks to it ...

'' has facilitated an increase of snake pipefish in that area. They breed in mid summer when the males and females pair up. They are ovoviviparous, the female attaches over 1,000 fertilised eggs, each about in diameter, to a layer of sticky mucus in a groove on the male's belly where they remain until they hatch. Following their birth the fry are pelagic until they attain a length of . The adults feed on small crustaceans and larval fish which are caught by being sucked into the mouth. It was noted when the populations of this species increased in the 2000s that some species of sea bird began to feed on the pipefish but found them rather indigestible due to their bony structure. Among those,

auk An auk or alcid is a bird of the family Alcidae in the order Charadriiformes. The alcid family includes the murres, guillemots, auklets, puffins, and murrelets. The word "auk" is derived from Icelandic ''álka'', from Old Norse ''alka'' (a ...

s and terns tried to feed these pipefish to their young as their more normal diet of

sand-eel Sand eel or sandeel is the common name used for a considerable number of species of fish. While they are not true eels, they are eel-like in their appearance and can grow up to in length. Many species are found off the western coasts of Europe ...

s, had declined. However, the pipefish have limited nutritional value compared to the oily-fleshed sand-eels and many chicks choked on their hard, rather indigestible bodies.

Etymology

The generic name ''Entelurus'' is derived from the Greek ''entelès'' which means "complete" and ''oura'' which means "tail" referring to the long tail which stretches out from the anus and his hardly differentiated from the body while the

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

is from the Latin ''aequoreus'' which means "marine".

References

External links

* {{Taxonbar, from=Q1548395 snake pipefish Fish of the North Atlantic Fish of the North Sea Fauna of the British Isles snake pipefish snake pipefish