Snailfish - WikiHQ

thumb|[[Liparis marmoratus]]

thumb|[[Liparis catharus]]

thumb|[[Liparis fabricii]]

The snailfishes or sea snails, are a family of marine ray-finned fishes. These fishes make up the Liparidae, a family classified within the order Scorpaeniformes.

Widely distributed from the Arctic to Antarctic Oceans, including the oceans in between, the snailfish family contains more than 30 genera and about 410 described species, but there are also many undescribed species. Snailfish are found at depths ranging from shallow coastal waters to more than , including in seven ocean trenches. The 5th edition of Fishes of the World classifies this family within superfamily Cyclopteroidea, part of the suborder Cottoidei of the order Scorpaeniformes. Other authorities do not recognise this superfamily and classify the two families within it, Cyclopteridae and Liparidae, within the infraorder Cottales alongside the sculpins, within the order Perciformes. An osteological analysis found that the genus Bathylutichthys was intermediate between the Psychrolutidae and the two families making up the Cyclopteroidea, meaning that those two families would not be supported as a superfamily within the Cottoidei.

Molecular biology

Species of deep-sea snailfish have been studied and compared to other ray-finned fishes (also known as teleosts) to analyze their adaptions to deep-sea conditions. The genomes of both the Yap hadal snailfish and Mariana hadal snailfish have been found to contain an abundance of the fmo3 gene, which produces the trimethylamine N-oxide (TMAO) protein stabilizer. Analysis of Yap hadal snailfish reveals a loss of olfactory receptors and gain of taste receptors, possibly due to the fairly restricted availability of food in the deep-sea. Additionally, perhaps due to lack of light in the deep sea, the Yap genome includes fewer copies of crystallin genes, which encode proteins that sense light and assist in focused vision, in comparison to other teleosts. Some species, such as Acantholiparis opercularis, have prickly spines as well. Their teeth are small and simple with blunt cusps. The deep-sea species have prominent, well-developed sensory pores on the head, part of the animals' lateral line system.

The pectoral fins are large and provide the snailfish with its primary means of locomotion, although they are fragile. In some species such as the antarctic Paraliparis devriesi, the pectoral fins have an expanded somatosensory system, including a taste bud.

Snailfish range in size from Paraliparis australis at to Polypera simushirae at some in length. The latter species may reach a weight of , but most species are smaller. Snailfish are of no interest to commercial fisheries.

alt=An adorable bumpy snailfish roaming the ocean happily|thumb|[[Careproctus colliculi]]

The deepest snailfish do not explode when brought to the surface, because they do not have a swim bladder. However, they do not survive capture, possibly due to molecular effects of depressurization. Many intact specimens have been retrieved in recent years for biochemical and anatomical study. Buoyancy without a swimbladder is due to gelatinous tissue and low-calcium bones. They are strictly found in cold waters, meaning that species of tropical and subtropical regions strictly are deepwater. They are common in most cold marine waters and are highly resilient, with some species, such as Liparis atlanticus and Liparus gibbus, having type-1 antifreeze proteins. It is the most species-rich family of fish in the Antarctic region, generally found in relatively deep waters (shallower Antarctic waters are dominated by Antarctic icefish).

The diminutive inquiline snailfish (Liparis inquilinus) of the northwestern Atlantic is known to live out its life inside the mantle cavity of the scallop Placopecten magellanicus. Liparis tunicatus lives amongst the kelp forests of the Bering Strait and the Gulf of St. Lawrence. The single species in genus Rhodichthys is endemic to the Norwegian Sea. Other species are found on muddy or silty bottoms of continental slopes.

Depth record

Although most snailfish live no deeper than the bathyal zone (less than deep), some live at greater depths than any other fish. In 2008, a UK-Japan team discovered a shoal of Pseudoliparis amblystomopsis snailfish at a depth of in the Japan Trench. These were, at the time, the deepest living fish ever recorded on film. The record was surpassed by snailfish filmed in the Mariana Trench at depths of in 2014 and in 2017, and at in the Izu–Ogasawara Trench in 2023. The species in these deepest records are unknown and may be undescribed, but have been referred to as "ethereal snailfish". The deepest-living described species is Pseudoliparis swirei, of the Mariana Trench, recorded at .

Snailfish (notably genera Notoliparis and Pseudoliparis) are the most common and dominant fish family in the hadal zone. Because of biochemical restrictions, is likely the maximum depth possible for any vertebrate. The larvae of some hadal snailfish species may spend time in open water at relatively shallow depths, less than .

Reproduction and life span

Reproductive strategies vary extensively among snailfish species, though it is thought that many abyssal benthic snailfish spawn seasonally and for relatively long intervals. It appears that all species lay relatively large eggs (diameter up to ) and the number of eggs is species dependent. Some species deposit their egg masses among cold-water corals, kelp, stones, or xenophyophores and males will sometimes guard the egg mass. At least one species, Careproctus ovigerus of the North Pacific, practices mouth brooding where the male snailfish carries the developing eggs around in his mouth. Some other species of the genus Careproctus, are parasitic, laying their eggs in the gill cavities of king crabs. The eggs put pressure on the crabs' gills which can cause the gill tissue to be damaged or die altogether. However, the survival of snailfish larvae has been shown to increase by the snailfish utilizing the crab host species as a way to care for and aerate their eggs. A different species, Careproctus rhodomelas, was found to be a batch spawner, laying multiple batches of large eggs multiple times throughout its lifetime.

After the eggs hatch, some species rapidly reach the adult size and only live for about one year, Otolith analysis (the investigation of snailfish ear bone) gives insight into longevity by seeing how it is broken into alternating translucent and opaque zones. This relays information about annual growth.

Little is known about snailfish courtship behavior but males of Careproctus pallidus are believed to wiggle their bodies as attractive or aggressive display. It is thought that in an environment so dark, it is hard to find and win contests for a mate. Therefore, snailfish use hydrodynamic signals that are felt by the mechanosensory lateral line to communicate.

Diet

Larval snailfish feed on a mix of plankton, small and large copepods, and amphipods. The larval diet of three Beaufort Sea snailfish species contained 28 food categories, mainly copepods and amphipods.

Snailfish prey fall into six main categories: gammarid, krill, natantian decapods, other crustaceans, fish, and others.

With the Okhotsk snailfish (Liparis ochotensis), the ratio between food intake and body weight changes as the organism grows; it is also highly seasonally variable. When the local environment experiences an increase in shrimp and crangonidae numbers, there is also a subsequent decrease in decapods. There are also snailfish localized to the Terpeniya Bay that purely eat zooplankton, setting them apart from other snailfish.

The ambush hunting methods employed by the Simushir snailfish (Polypera simushirae) are unique among snailfish. They have the ability to blend into the ground, waiting to surprise the next organism to wander into their path. The top prey for this species are fish, making up 97.7% of their overall food intake.

Genera

This family contains these genera as of 2020:

Allocareproctus Pitruk & Fedorov, 1993
Careproctus Krøyer, 1862
Crystallias Jordan & Snyder, 1902
Crystallichthys Jordan & Gilbert, 1898
Eknomoliparis Stein, Meléndez C. & Kong U., 1991
Elassodiscus Gilbert & Burke, 1912
Eutelichthys Tortonese, 1959
Genioliparis Andriashev & Neyelov, 1976
Gyrinichthys Gilbert, 1896
Liparis Scopoli, 1777
Lipariscus Gilbert, 1915
Lopholiparis Orr, 2004
Menziesichthys Nalbant & Mayer, 1971
Nectoliparis Gilbert & Burke, 1912
Notoliparis Andriashev, 1975
Osteodiscus Stein, 1978
Palmoliparis Balushkin, 1996
Paraliparis Collett, 1879
Polypera Burke, 1912
Praematoliparis Andriashev, 2003
Prognatholiparis Orr & Busby, 2001
Psednos Barnard, 1927
Pseudoliparis Andriashev, 1955
Pseudonotoliparis Pitruk, 1991
Rhinoliparis Gilbert, 1896
Rhodichthys Collett, 1879
Squaloliparis Pitruk & Fedorov, 1993
Temnocora Burke, 1930
Volodichthys Balushkin, 2012

Image:Acantholiparis opercularis.jpg|Acantholiparis opercularis

Image:Careproctus ovigerum (juvenile).jpg|Careproctus ovigerus (juvenile)

Image:Crystallichthys cyclospilus.jpg|Crystallichthys cyclospilus

Image:Elassodiscus tremebundus.jpg|Elassodiscus tremebundus

Image:GelatinousSeasnail.jpg|Liparis fabricii

Image:Nectoliparis pelagicus.jpg|Nectoliparis pelagicus

Image:Paraliparis bathybius1.jpg|Paraliparis bathybius

Image:Rhodichthys regina1.jpg|Rhodichthys regina

Image:Temnocora candida.jpg|Temnocora candida

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References

External links