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 ; 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 craniallateral 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 in the case of Lethotremus awae up to more than in the case of the common lumpsucker Cyclopterus lumpus. and Eumicrotremus orbis'' demonstrating adhesive pelvic discs.
Habitat and diet
As their appearance might suggest, lumpsuckers are poor 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 colouration allows for effective camouflage. Members of the family are found primarily on the continental shelf or slope, at depths down to. Some of the deeper-living species are however pelagic, remaining some distance above the ocean floor. Benthic species feed on 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 ; this may well be true of all species. Males are also known to guard the brood of spherical eggs. One of the peculiarities of Lumpsuckers' neural system is that they lack Mauthner cell neurons in their hindbrain, while these cells are present in virtually all other teleost fish. Nevertheless, the lumpsuckers do have a C-startle response, which is apparently mediated by other hindbrain cells. 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.
Fishers and the lumpsucker industry
Cyclopterus lumpus plays an important role in the Icelandic fishing industry; Lotna ehf, a fishing company partly owned by Everton midfielder Gylfi Sigurðsson, has recorded catches of lumpfish as large as 2 tonnes. Other fish often caught on trawlers simultaneously with lumpfish include cod. Lumpfish are also investigated in combating the effects of sea lice infections on salmon farming operations.
