The smooth lumpfish (''Aptocyclus ventricosus'') is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of lumpfish native to the

North Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

where it is found at depths down to . This species grows to a length of TL. It is the only known member of its

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

Description

The smooth lumpfish, or smooth lumpsucker, is a deep sea fish species with a body length of and body weight of on average. They look brownish gray with dark spots dorsally, muddy gray ventrally. They have naked skin without scales and tubercles. A smooth lumpfish has no dorsal spines or anal spines, eight to nine dorsal soft rays, and seven to nine anal soft rays. They have a rounded caudal fin and large and broadly based pectoral fins. Their pelvic fins are modified to form a clinging disc with a thickened margin on the ventral surface of the body. They have their first dorsal fins completed embedded under the skin.

Habitat and Diet

Smooth lumpfish are widely distributed throughout the

, especially in the Aleutian Basin. They inhabit both near-bottom and mid-water layers, ranging from 5to 1,700m. They are preyed upon by certain fish species, marine mammals and

seabirds Seabirds (also known as marine birds) are birds that are adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same envi ...

. Their preferred diet consists of

medusa In Greek mythology, Medusa (; Ancient Greek: Μέδουσα "guardian, protectress"), also called Gorgo, was one of the three monstrous Gorgons, generally described as winged human females with living venomous snakes in place of hair. Those ...

and

ctenophores Ctenophora (; ctenophore ; ) comprise a phylum of marine invertebrates, commonly known as comb jellies, that inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming (commonly referred to as "combs"), a ...

, and they occasionally also feed on pelagic

polychaetes Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made ...

and

crustaceans Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...

Reproduction

The smooth lumpfish is an

iteroparous Semelparity and iteroparity are two contrasting reproductive strategies available to living organisms. A species is considered semelparous if it is characterized by a single reproductive episode before death, and iteroparous if it is characteri ...

gonochoristic species with determinate

fecundity Fecundity is defined in two ways; in human demography, it is the potential for reproduction of a recorded population as opposed to a sole organism, while in population biology, it is considered similar to fertility, the natural capability to pr ...

, group-synchronous ovary organization, total

spawning Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquat ...

(release of 1 batch of eggs per breeding season), and

external fertilization External fertilization is a mode of reproduction in which a male organism's sperm fertilizes a female organism's egg outside of the female's body. It is contrasted with internal fertilization, in which sperm are introduced via insemination and then ...

. Smooth lumpfish perform spawning migration from deep-ocean to coastal zones, where breeding occurs over a rocky bottom at depths shallower than . A thick envelope protects these demersal eggs from mechanical damage during development in the coastal zone. The incubation time between fertilization and hatching is more than 40days. Males protect the egg clusters after females spawn.Zhukova, K., Maznikova, O. A., & Orlov, A. M. (2018). Gonadal maturation of the female smooth lumpsucker (Aptocyclus ventricosus). Fishery Bulletin, 116(2), 153-160. doi:10.7755/fb.116.2.4

References

Cyclopteridae Monotypic fish genera Fish described in 1769 Taxa named by Peter Simon Pallas Fish of the North Pacific Fish of the Bering Sea {{Scorpaeniformes-stub