Lumpsucker
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Aptocyclus |
Lumpsuckers or Lumpfish are mostly small scorpaeniform marine fish of the family Cyclopteridae. Found in the cold waters of the Arctic, North Atlantic, and North Pacific oceans, the family contains approximately 28 species in six genera. The greatest number of species are found in the North Pacific.
The roe of larger species is used extensively in Danish cuisine, where the fish are known as stenbider.
The family name Cyclopteridae derives from the Greek words kyklos meaning "circle" and pteryx meaning "fin".
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Physical description
Lumpsuckers are named appropriately enough; their portly bodies are nearly spherical with generally drab coloration and lithic patterns. The "sucker" part refers to the fish's modified pelvic fins, which have evolved into adhesive discs (located ventrally, behind the pectoral fins); the fish use these discs to adhere to the substrate. Many species have bony, wart-like tubercles adorning the head and body; these are important taxonomic features of the family.
The simple, rounded fins are small with the exception of the broad, fan-like pectorals, which actually extend ventrally. The first of the two dorsal fins is spinous, with 4-8 spines; in some species, this fin is completely overgrown with skin and therefore not visible. While the lateral line in Lumpsuckers is otherwise reduced or absent, it is well developed in the head; some species even have tubular, whisker-like external projections of the opercular canal, which is a part of the cranial lateral line system.
The relatively small mouths of Lumpsuckers are lined with narrow rows of small conical teeth. The gas bladder is absent. In terms of length, Lumpsuckers range in size from two centimetres in Lethotremus awae to 60 centimetres in Cyclopterus lumpus (known commonly as simply the Lumpsucker). With the exception of the Smooth Lumpsucker (Aptocyclus ventricosus) at 40.5 centimetres, all other species are under 14 centimetres in length.
Habitat and diet
As their appearance might suggest, Lumpsuckers are not good swimmers. Most species are benthic; that is, they spend most of their time on or near the bottom. The fish are found on rocky or muddy substrates, where their coloration allows for effective camouflage. Members of the family are found primarily on the continental shelf or slope, at depths from 100-1,700 metres. Some of the deeper-living species are however pelagic, remaining some distance above the ocean floor.
Benthic species dine upon sessile invertebrates such as polychaete worms, crustaceans and mollusks. Pelagic species target prey they are capable of overtaking, namely slow-moving jellyfish and ctenophores.
Behaviour and reproduction
Lumpsuckers are a poorly studied group, with little known of their behaviour and biology. At least some species are known to travel great distances in order to spawn in shallow, intertidal waters (from December to June in the Smooth Lumpsucker); this may well be true of all species. Males are also known to guard the brood of spherical eggs.
Hatchlings have well-developed pectoral fins and adhesive pelvic discs, which the fish use to cling to rocks in shallow water. Young fish remain in shallow, warmer water until fully developed. Pacific cod and Sablefish are known predators of Lumpsuckers, the latter capable of inflating themselves with water, presumably as a defensive tactic.
See also
External link
- FishBase entry on Cyclopteridae (http://www.fishbase.org/Summary/FamilySummary.cfm?ID=284)