Cyclopteridae

The Cyclopteridae are a family of marine fishes, commonly known as lumpsuckers or lumpfish, in the order Scorpaeniformes. They are found in the cold waters of the Arctic, North Atlantic, and North Pacific oceans. The greatest number of species are found in the North Pacific. The family name Cyclopteridae derives from the Greek words κύκλος (kyklos), meaning "circle", and πτέρυξ (pteryx), meaning "wing" or "fin", in reference to the circle-shaped pectoral fins of most of the fish in this family.

Lumpsuckers
Cyclopterus lumpus
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Scorpaeniformes
Superfamily: Cyclopteroidea
Family: Cyclopteridae
Bonaparte, 1831
Genera

Aptocyclus De la Pylaie, 1835
Cyclopsis Popov, 1930
Cyclopteropsis Soldatov & Popov, 1929
Cyclopterus Linnaeus, 1758
Eumicrotremus Gill, 1862
Georgimarinus Voskoboinikova & Nazarkin, 2015[1]
Lethotremus Gilbert, 1896
Microancathus Voskoboinikova, 2015[2]

Description
Aptocyclus ventricosus, inflated due to barotrauma

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 2 cm (0.79 in) in the case of Lethotremus awae up to more than 50 cm (1 ft 8 in) in the case of the common lumpsucker Cyclopterus lumpus.

Eumicrotremus phrynoides 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 1,700 m (5,600 ft). 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 (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.

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.[3]

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

The only species that is targeted commercially is Cyclopterus lumpus, which is targeted primarily for its roe in Canada, Greenland, Iceland, and Norway, and to a lesser extent in Denmark and Sweden. Cyclopterus lumpus are also caught from the wild to provide broodstock for the aquaculture industry where the fish is used as a cleaner fish to remove sea lice in salmon aquaculture.

Species
Eumicrotremus phrynoides
Eumicrotremus orbis
Lethotremus awae

There are about 30 species in seven genera:

References
  1. Voskoboinikova O.S., Nazarkin M.V. (2015). "Georgimarinus gen. nov. A New Genus of the Family Cyclopteridae (Cottoidei)". Journal of Ichthyology. 55 (5): 630–635. doi:10.1134/s003294521505015x.
  2. Voskoboinikova O.S. (2015). "New genus of the family Cyclopteridae – Microancathus gen. n. (Pisces: Cottoidei: Cyclopteridae) with description of a new species Microancathus tokranovi sp. n.". Proceedings of the Zoological Institute of the Russian Academy of Sciences. 319 (2): 215–228.
  3. Hale, M.E. (2000). "Startle responses of fish without Mauthner neurons: escape behavior of the lumpfish (Cyclopterus lumpus)". Biological Bulletin. 199 (2): 180–182. doi:10.2307/1542886. PMID 11081724.
  4. Voskoboinikova O.S., Nazarkin M.V. (2015). "Redescription of Andriashev's Spiny Pimpled Lumpsucker Eumicrotremus andriashevi and Designation of a New Subspecies E. andriashevi aculeatus ssp. n. (Cyclopteridae)". Journal of Ichthyology. 55 (2): 155–161. doi:10.1134/s0032945215020174.
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