The viviparous eelpout (''Zoarces viviparus''), also known as the, viviparous blenny and European eelpout is species of marine ray-finned fish belonging to the family Zoarcidae, the eelpouts. It is notable for being ovoviviparous and gives birth to live larvae (hence the description "mother of eels"). It is a common

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ingredient in Mediterranean countries. The bones are of greenish colour, due to a harmless pigment. Their skin is slimy and the colour is variable.

Taxonomy

The viviparous eelpout was first formally described as ''Blennius viviparus'' by Carl Linnaeus in the 10th edition of his ''

Systema Naturae ' (originally in Latin written ' with the ligature æ) is one of the major works of the Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the system, now known as binomial nomen ...

'' with its type locality given as "European seas". In 1829, the French zoologist

Georges Cuvier Jean Léopold Nicolas Frédéric, Baron Cuvier (; 23 August 1769 – 13 May 1832), known as Georges Cuvier, was a French natural history, naturalist and zoology, zoologist, sometimes referred to as the "founding father of paleontology". Cuvier ...

proposed the genus '' Zoarces'' for the eelpouts and subsequently ''B, viviparus'' was descignated as the type species of ''Zoarces'', possibly by

David Starr Jordan David Starr Jordan (January 19, 1851 – September 19, 1931) was the founding president of Stanford University, serving from 1891 to 1913. He was an ichthyologist during his research career. Prior to serving as president of Stanford Univer ...

in 1917/ 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 ...

''viviparus'' means "giving birth to live young", although the species is ovoviviparous.

Description

The viviparous eelpout has a slim, tapering body and resembles a small burbot (''Lota lota''), a wide head and mouth and protuberant lips. It has long, ribbon-like dorsal and anal fins which continue on to unite with the arrowhead-shaped caudal fin. This distinguishes this fish from the two similar slim-bodied bottom-dwelling fish of the area, the

rock gunnel The rock gunnel (''Pholis gunnellus''), or butterfish, is a species of marine ray-finned fish belonging to the family Pholidae, the gunnels. This species is found in the coastal waters of the North Atlantic Ocean and in the Atlantic part of the Ar ...

(''Pholis gunnellus'') and the

snake blenny Snake blenny (''Ophidion barbatum'') is a fish species in the family Ophidiidae. It is widespread in the eastern Atlantic from southern England to Senegal in West Africa, and the northern Mediterranean. It is a marine subtropical demersal fish, ...

(''Ophidion barbatum''). The bones are green. The tiny scales are embedded in the slimy skin. There dorsal fin becomes lower as it nears the caudal fin with these shorter rays being short and spinous. The colour is highly variable, although they are commonly greyish brown on the upper body and yellowish ventrally. They are marked with eithaer a single or double series of blotches along the body and on the dorsal fin. The pectoral fins have yellow or yellowish orange edges. This species reaches a maximum published total length of , although is more typical, and may weigh up to .

Distribution and habitat

The viviparous eelpoutis found in the eastern Atlantic Ocean where its range extends from the English Channel north around the British Isles, although it is absent from the Atlantic coasts of Ireland, eastrds onto the Baltic Sea and northwards through the North Sea and along the coast of Norway to the White Sea and the Barents Sea. This species occurs in the intertidal zone where it can live in marine and brackish environments, avoiding drying out when exposed at low tide by sheltering beneath rocks or in fissures in the rock or by staying submerged in

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s. This

demersal fish Demersal fish, also known as groundfish, live and feed on or near the bottom of seas or lakes (the demersal zone).Walrond Carl . "Coastal fish - Fish of the open sea floor"Te Ara - the Encyclopedia of New Zealand. Updated 2 March 2009 They occ ...

is normally sedentary, hiding under rocks or among seaweed. Its can be found at depsth between , although it is normally found at depths of . Zoarces viviparus

Biology

The viviparous eelpout feeds on bottom-dwelling invertebrates, such as crustaceans, and fish eggs and fry. Adults mate during the months of August and September using internal fertilisation. The fish are notably viviparous, giving birth to 30–400 live developed young. Unusually, it does so during winter when water temperatures are extremely cold. Among fish it has one of the longest known pregnancies, lasting approximately six months. It has been discovered that the eelpout suckles its young embryos while still within their mother's body, making it the only fish species to suckle its offspring. The embryos actually suckle from ovarian follicles, ingesting nutrients and gases from these internal structures. After depleting the egg's yolk reserves, the eelpouts attach their mouths to an ovarian follicle, which has a canal in its tip via which fluid and nutrients can flow. This follicle fluid is rich in proteins, fatty acids and glucose. It is also saturated in oxygen, which helps ventilate the gills of the developing fish. Each embryo latches onto a single follicle. This ensures an equal distribution of nutrients.

Utilisation

The viviparous eelpout is of minor commercial value to fisheries in some parts of its range.

References

{{Taxonbar, from=Q27336 Zoarces Fish described in 1758 Taxa named by Carl Linnaeus Fish of the Arctic Ocean Fish of the Atlantic Ocean Fish of the Baltic Sea Fish of the North Sea Fish of Europe Fish of Russia Viviparous fish