Snailfish
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Acantholiparis |
Snailfish are scorpaeniform marine fish of the family Liparidae. Widely distributed from the Arctic to Antarctic Oceans including the northern Pacific, the snailfish family contains approximately 23 genera and 195 species. They are closely related to the sculpins of the family Cottidae and the lumpfish of the family Cyclopteridae; snailfish are sometimes included within the latter family.
The snailfish family is poorly studied and few specifics are known. Their elongate, tadpole-like bodies are similar in profile to the rattails. Their heads are large with small eyes; their bodies are slender to deep, tapering to a very small tail. The extensive dorsal and anal fins may merge or nearly merge with the tail fin. Snailfish are scaleless with a thin, loose gelatinous skin; some species, such as the spiny snailfish (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 of the head, part of the animals' lateral line system.
The pectoral fins are large and provide the snailfish with its primary means of locomotion. They are benthic fish with pelvic fins modified to form an adhesive disc; this nearly circular disc is absent in Paraliparis and Nectoliparis species. Snailfish range in size from Paraliparis australis at 5 centimetres to Polypera simushirae at some 77 centimetres in length. The latter species may reach a weight of 11 kilograms, but most species are toward the smaller end of this range. Snailfish are of no interest to commercial fisheries.
The habitats chosen by snailfish are as widely variable as their size; they are found in both shallow intertidal zones and at fantastic depths of 7,500 metres or more, in both cold and warm waters. 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. The kelp snailfish (Liparis tunicatus) lives amongst the kelp forests of the Bering Strait and the estuary of the St. Lawrence River. Other species are found on muddy or silty bottoms of continental slopes. Snailfish are abundant in most (especially polar) waters and are highly resilient.
Reproductive strategies are also known to vary among the species. At least one species, the abyssal snailfish (Careproctus ovigerum) of the North Pacific, is known to practice mouth brooding; that is, the male of the species carries the developing eggs around in his mouth. All species are known to lay a small number (c. 300) of relatively large eggs (4.5-8 mm in diameter). Other species of the genus Careproctus lay their eggs in the gill cavities of king crabs.
The diet of snailfish consists primarily of small benthic crustaceans, mollusks, polychaete worms, and other small invertebrates. Some species are also piscivorous. Specialist species such as Paraliparis rosaceus feed exclusively on sea cucumbers.
External links
- FishBase entry on Liparidae (http://www.fishbase.se/Summary/FamilySummary.cfm?ID=615)
- Clear ROV images of a deep-sea snailfish in Monterey Canyon (http://www.mbari.org/~jdrazen/fish%20pages/liparidae.htm)