Viviparous eelpout

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Viviparous eelpout
3 specimens of Zoarces viviparus.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Zoarcidae
Genus: Zoarces
Species:
Z. viviparus
Binomial name
Zoarces viviparus
Synonyms [2]
  • Blennius viviparusLinnaeus, 1758

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

Contents

Taxonomy

The viviparous eelpout was first formally described as Blennius viviparus by Carl Linnaeus in the 10th edition of his Systema Naturae with its type locality given as "European seas". [3] In 1829, the French zoologist Georges 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 in 1917/ [4] The specific name viviparus means "giving birth to live young", although the species is ovoviviparous. [5]

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 (Pholis gunnellus) and the snake blenny (Ophidion barbatum). The bones are green. [6] 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. [7] This species reaches a maximum published total length of 52 cm (20 in), although 30 cm (12 in) is more typical, and may weigh up to 510 g (18 oz). [2]

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, [1] although it is absent from the Atlantic coasts of Ireland, [8] eastwards onto the Baltic Sea and northwards through the North Sea and along the coast of Norway to the White Sea and the Barents Sea. [1] 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 rock pools. This demersal fish is normally sedentary, hiding under rocks or among seaweed. [8] Its can be found at depsth between 0 and 40 m (0 and 131 ft), although it is normally found at depths of 2 to 20 m (6 ft 7 in to 65 ft 7 in). [2]

Drawing of the eelpout with fry Zoarces viviparus.jpg
Drawing of the eelpout with fry

Biology

The viviparous eelpout feeds on bottom-dwelling invertebrates, such as crustaceans, and fish eggs and fry. [6]

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. [9]

Utilisation

The viviparous eelpout is of minor commercial value to fisheries in some parts of its range. [1]

Related Research Articles

The eelpouts are the ray-finned fish family Zoarcidae. As the common name suggests, they are somewhat eel-like in appearance. All of the 300 species are marine and mostly bottom-dwelling, some at great depths. Eelpouts are predominantly found in the Northern Hemisphere. The Arctic, north Pacific and north Atlantic oceans have the highest concentration of species; however, species are found around the globe.

Zoarces is a genus of marine ray-finned fishes belonging to the family Zoarcidae, the eelpouts. It is the only genus in the subfamily Zoarcinae. These eelpouts are found in the northern Atlantic and northern Pacific Oceans.

<span class="mw-page-title-main">Zoarcoidei</span> Suborder of ray-finned fishes

Zoarcoidei is a suborder of marine ray-finned fishes belonging to the order Perciformes. The suborder includes the wolffishes, gunnels and eelpouts. The suborder includes about 400 species. These fishes predominantly found in the boreal seas of the northern hemisphere but they have colonised the southern hemisphere.

Zoarces elongatus, the eastern viviparous blenny, is an eelpout in the family Zoarcidae, described by Rudolf Kner in 1868. The species is endemic to the Northwest Pacific, in such areas as the Sea of Japan and the Sea of Okhotsk and China.

<span class="mw-page-title-main">Pregnancy in fish</span>

Pregnancy has been traditionally defined as the period of time eggs are incubated in the body after the egg-sperm union. Although the term often refers to placental mammals, it has also been used in the titles of many international, peer-reviewed, scientific articles on fish. Consistent with this definition, there are several modes of reproduction in fish, providing different amounts of parental care. In ovoviviparity, there is internal fertilization and the young are born live but there is no placental connection or significant trophic (feeding) interaction; the mother's body maintains gas exchange but the unborn young are nourished by egg yolk. There are two types of viviparity in fish. In histotrophic viviparity, the zygotes develop in the female's oviducts, but she provides no direct nutrition; the embryos survive by eating her eggs or their unborn siblings. In hemotrophic viviparity, the zygotes are retained within the female and are provided with nutrients by her, often through some form of placenta.

<i>Lycodichthys</i> Genus of fishes

Lycodichthys is a genus of marine ray-finned fish belonging to the family Zoarcidae, the eelpouts. They are found in the Southern Ocean.

Lycodinae is a subfamily of marine ray-finned fish belonging to the family Zoarcidae, the eelpouts. These eelpouts are found are in all the world's oceans, with a number of species being found off southern South America.

Argentinolycus is a monospecific genus of marine ray-finned fish belonging to the family Zoarcidae, the eelpouts. Its only species is Argentinolycus elongatus which is found in coastal southern eastern South America.

<i>Austrolycus</i> Genus of fishes

Austrolycus is a genus of marine ray-finned fishes belonging to the family Zoarcidae, the eelpouts. The two species in this genus are found in the southeastern Pacific Ocean and the western South Atlantic Ocean off southern South America and the Falkland Islands.

Bellingshausenia is a monospecific genus of marine ray-finned fish belonging to the family Zoarcidae, the eelpouts. Its only species is Bellingshausenia olasoi which is only known from the Bellingshausen Sea in the Southern Ocean.

The cuskpout is a species of marine ray-finned fish belonging to the family Zoarcidae, the eelpouts. It is the only species in the monospecific genus Derepodichthys and is found in the eastern North Pacific Ocean.

<i>Iluocoetes</i> Genus of fishes

Iluocoetes is a monospecific genus of marine ray-finned fish belonging to the family Zoarcidae, the eelpouts. The only species in the genus is Iluocoetes fimbriatus. This species is found off southern South America, off Chile and Argentina, in the southeastern Pacific and southwestern Atlantic Oceans.

<i>Lycenchelys muraena</i> Species of fish

Lycenchelys muraena, the moray wolf eel, is a species of marine ray-finned fish belonging to the family Zoarcidae, the eelpouts. It is found in the Arctic and North Atlantic Oceans.

Lycodes gracilis, Vahl's eelpout or the gracile eelpout, is a species of marine ray-finned fish belonging to the family Zoarcidae, the eelpouts. It is found in the eastern North Atlantic Ocean and adjacent areas of the Arctic Ocean.

Lycodes esmarkii, Esmark's eelpout or the greater eelpout, is a species of marine ray-finned fish belonging to the family Zoarcidae, the eelpouts. This species is found in the North Atlantic Ocean.

Lycodonus is a genus of marine ray-finned fish belonging to the family Zoarcidae, the eelpouts. The species in this genus are found in the North and Southern Atlantic Ocean. These fishes are sometimes called scutepouts.

<i>Lycogrammoides</i> Monospecific genus of marine ray-finned fish

Lycogrammoides is a monospecific genus of marine ray-finned fish belonging to the family Zoarcidae, the eelpouts. Its only species is Lycogrammoides schmidti, a rare species of the Sea of Okhotsk in the northwestern Pacific Ocean.

The bearded eelpout is a species of marine ray-finned fish belonging to the family Zoarcidae, the eelpouts. This species is the only species in the monospecific genus Lyconema. It is found in the eastern Pacific Ocean.

Lycozoarces is a monospecific genus of marine ray-finned fish belonging to the family Zoarcidae, the eelpouts, its only species being Lycozoarces regani. It is the only genus in the monogeneric subfamily Lycozoarinae. This taxon occurs in the northwestern Pacific Ocean in the Sea of Okhotsk and the Tatar Strait in the northern Sea of Japan.

<i>Pyrolycus jaco</i> Species of eelpout

Pyrolycus jaco is a species of eelpout. These organisms are typically distinguished by their eel-like morphology and, in certain species, facial features that evoke an appearance of "pouting". This species was discovered at Jacó Scar, hydrothermal seep site in the Pacific Ocean.

References

  1. 1 2 3 4 Nielsen, J.; Knudsen, S.; Uiblein, F. (2015). "Zoarces viviparus". IUCN Red List of Threatened Species . 2015: e.T18181090A45904990. Retrieved 23 November 2022. Scope: Europe
  2. 1 2 3 Froese, Rainer; Pauly, Daniel (eds.). "Zoarces viviparus". FishBase . June 2022 version.
  3. ↑ Eschmeyer, William N.; Fricke, Ron & van der Laan, Richard (eds.). "Species in the genus Genus+Zoarces". Catalog of Fishes . California Academy of Sciences . Retrieved 23 November 2022.
  4. ↑ Eschmeyer, William N.; Fricke, Ron & van der Laan, Richard (eds.). "Genera in the family Zoarcinae". Catalog of Fishes . California Academy of Sciences . Retrieved 23 November 2022.
  5. ↑ Christopher Scharpf & Kenneth J. Lazara, eds. (6 May 2022). "Order Perciformes Suborder Cottoidea: Infraorder Zoarcales: Family: Zoarcidae". The ETYFish Project Fish Name Etymology Database. Christopher Scharpf and Kenneth J. Lazara. Retrieved 23 November 2022.
  6. 1 2 "Viviparous blenny: Zoarces viviparus (L.)". NatureGate. Retrieved 2013-12-19.
  7. ↑ J-C Huraeu. "Viviparous eelpout (Zoarces viviparus)". Fishes of the NE Atlantic and the Mediterranean. Marine Species Identification Portal. Retrieved 23 November 2022.
  8. 1 2 Bilewitch, J. (2009). Tyler-Walters H. and Hiscock K. (eds.). "Zoarces viviparus Viviparous eelpout". Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. Retrieved 23 November 2022.
  9. ↑ Matt Walker (September 28, 2010). "Pregnant European eelpout fish suckles young embryos". BBC News . Retrieved September 29, 2010.
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