{{Short description|Species of fish}} {{Speciesbox | image = Entelurus aequoreus.jpg | image_caption = | status = LC | status_system = IUCN3.1 | status_ref = <ref name = IUCN>{{cite journal | author = Schultz, J. | year= 2014 | title = ''Entelurus aequoreus'' | journal = The IUCN Red List of Threatened Species | volume = 2014 | page = e.T18258072A44775951 | doi= 10.2305/IUCN.UK.2014-3.RLTS.T18258072A44775951.en | doi-access = free }}</ref> | parent_authority = A. H. A. Duméril, 1870 | display_parents = 2 | genus = Entelurus | species = aequoreus | authority = (Linnaeus, 1758) | synonyms = ''Syngnathus aequoreus'' <small>Linnaeus, 1758</small> }}
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 pipefishes by the near lack of bony rings. It has a long head,<ref name = Wheeler/> with a thin dark stripe in its sides,<ref name = MSIP/> with a long, concave snout and a very small, protractile mouth.<ref name = DORIS>{{cite web | url = http://doris.ffessm.fr/ref/specie/870 | title = Entélure ''Entelurus aequoreus'' (Linnaeus, 1758) | access-date = 29 May 2018 | publisher = Données d'Observations pour la Reconnaissance et l'Identification de la faune et la flore Subaquatiques | language = French}}</ref> The long based dorsal fin has 37–47 short rays while the caudal fin is minute and there are no pectoral fins or anal fins. 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.<ref name = Wheeler>{{cite book | author = Alwyne Wheeler | author-link = Alwynne Cooper Wheeler | year = 1992 | title = The Pocket Guide to Salt Water Fishes of Britain and Europe | publisher = Parkgate Books | edition = 1997 | isbn = 978-1855853645 | page = 138}}</ref><ref name = MSIP>{{cite web | url = http://species-identification.org/species.php?species_group=fnam&id=2189 | title = Fishes of the NE Atlantic and Mediterranean | access-date = 29 May 2018 | publisher = ETI Bioinformatics | editor = J.C. Hureau | work = Marine Species Identification Portal | page = Snake pipefish (''Entelurus aequoraeus'')}}</ref> The opening to the gills has been reduced to a pore in the membrane above the opercle and the gill membranes are fused to the body and the isthmus. They can grow to total lengths of {{convert|40|cm|in}} in males and {{convert|60|cm|in}} in females, although they are more commonly around {{convert|32|cm|in}} and {{convert|45|cm|in}} respectively.<ref name = FishBase>{{FishBase|Entelurus|aequoreus|month=February|year=2018}}</ref> The juveniles of less than 70 mm in length have membranous pectoral fins which disappear as they mature.<ref name = DORIS/>
==Distribution== The snake pipefish occurs in the north eastern Atlantic from Iceland and Norway to the Azores, into the Baltic Sea.<ref name = IUCN/> In the early 2000s it expanded its range northwards as far as Svalbard and the Barents Sea.<ref name = Fleischer>{{cite journal | author1 = Dirk Fleischer | author2 = M. Schaber | author3 = D. Piepenburg | name-list-style = amp | year = 2007 | title = Atlantic snake pipefish (Entelurus aequoreus) extends its northward distribution range to Svalbard (Arctic Ocean) | journal = Polar Biology | volume = 30 | issue = 10 | pages = 1359–1362| doi = 10.1007/s00300-007-0322-y | s2cid = 40670548 }} Abstract</ref> It is not found in the Mediterranean Sea.<ref name = seawater>{{cite web | url = http://www.seawater.no/fauna/chordata/aequoreus.html | title = Snake Pipefish - ''Entelurus aequoreus'' | access-date = 29 May 2018 | publisher = Kåre Telnes | work = The Marine Flora & Fauna of Norway}}</ref>
==Habitat and biology== The snake pipefish occurs in more open and deeper water than other species of pipefish, with a depth range of {{convert|10-100|m|ft}} and it lives among kelp and other types of deep water sea weeds, as well as sea grass such as ''Zostera marina'',<ref name = IUCN/> but some individuals both young and large adults have been caught in pelagic waters.<ref name = Wheeler/> Its colour and patterning provides good camouflage in such habitats.<ref name = Macduff>{{cite web | url = http://www.macduff-aquarium.org.uk/explore/fish-finder/snake-pipefish | title = Snake Pipefish ''Entelurus aequoreus'' | access-date = 28 May 2018 | publisher = Macduff Aquarium}}</ref> The colonisation of the Waddensee sand flats by the invasive Japanese seaweed ''Sargassum muticum'' has facilitated an increase of snake pipefish in that area.<ref name = Polle>{{cite journal | author1 = Patrick Polle | author2 = Christian Buschbaum | name-list-style = amp | year = 2008 | title = Native pipefish ''Entelurus aequoreus'' are promoted by the introduced seaweed ''Sargassum muticum'' in the northern Wadden Sea, North Sea | url = https://www.int-res.com/articles/ab2008/3/b003p011.pdf | journal = Aquatic Biology | volume = 3 | pages = 11–18| doi = 10.3354/ab00071 }}</ref>
They breed in mid summer when the males and females pair up.<ref name = Wheeler/> They are ovoviviparous,<ref name = FishBase/> the female attaches over 1,000<ref name = IUCN/> fertilised eggs, each about {{convert|1.2|mm|in}} in diameter,<ref name = MSIP/> to a layer of sticky mucus in a groove on the male's belly where they remain until they hatch.<ref name = Macduff/><ref name = Wheeler/> Following their birth the fry are pelagic until they attain a length of {{convert|12|mm|in}}.<ref name = DORIS/> The adults feed on small crustaceans and larval fish<ref name = IUCN/> which are caught by being sucked into the mouth.<ref name = Macduff/> 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, auks and terns tried to feed these pipefish to their young as their more normal diet of sand-eels, 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.<ref name = oceaneye>{{cite web | url = http://www.oceaneyephoto.com/photo_409982.html | title = Snake Pipefish - Entelurus aequoreus | access-date = 29 May 2018 | publisher = British Marine Life}}</ref>
==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 how it's hardly differentiated from the body while the specific name is from the Latin ''aequoreus'' which means "marine".<ref name = DORIS/>
==References== {{Reflist}}
==External links== * {{Commons category-inline}}
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snake pipefish Category:Fish of the North Atlantic Category:Fish of the North Sea Category:Fauna of the British Isles snake pipefish snake pipefish