The Gonatidae, also known as armhook squid, are a

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

of moderately sized

squid True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting t ...

. The family contains about 19

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 ...

in three

genera 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 nomenclat ...

, widely distributed and plentiful in cold boreal waters of the

Pacific Ocean 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 ...

. At least one species is known from

Antarctic The Antarctic ( or , American English also or ; commonly ) is a polar region around Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica, the Kerguelen Plateau and other ...

waters, and two from the

North Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Africa, Europe and ...

. The genus ''

Eogonatus ''Gonatopsis'' is a genus of squid from the family Gonatidae. They are characterised by the loss of their tentacles by the time they have reach the subadult stage. They have arms which have two series of hooks along the midline of the oral surfa ...

'' was created for the species known as ''

Eogonatus tinro ''Gonatopsis okutanii'' is a species of squid from the family Gonatidae from the northern Pacific Ocean. It is of uncertain taxonomic status, the presence of remnant tentacles on spent females indicate that this species does not belong in the ge ...

'' because it did not have hooks on the

tentacular club All cephalopods possess flexible limbs extending from their heads and surrounding their beaks. These appendages, which function as muscular hydrostats, have been variously termed arms, legs or tentacles. Description In the scientific l ...

and it has 5 rows of teeth on the radula. Molecular studies in

allozymes Alloenzymes (or also called allozymes) are variant forms of an enzyme which differ structurally but not functionally from other allozymes coded for by different alleles at the same locus. These are opposed to isozymes, which are enzymes that perfo ...

and

mitochondrial DNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...

have indicated that this species nests within the genus ''

Gonatus ''Gonatus'' is a genus of squid in the family Gonatidae, comprising twelve species, and therefore containing the most species in the family. Adult squid belonging to species in this genus are notable for their lack of tentacles. The genus contai ...

'', although other authorities treat it as a

synonym A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

of ''

Gonatopsis okutanii ''Gonatopsis okutanii'' is a species of squid from the family Gonatidae from the northern Pacific Ocean. It is of uncertain taxonomic status, the presence of remnant tentacles on spent females indicate that this species does not belong in the ge ...

''.

Description

Morphologically, armhook squid are fairly uniform: all species are characterised by the suckers of their

arm In human anatomy, the arm refers to the upper limb in common usage, although academically the term specifically means the upper arm between the glenohumeral joint (shoulder joint) and the elbow joint. The distal part of the upper limb between th ...

s, which are arranged in four rows (series) rather than the typical count of two. In most species, the arm's two mesial rows of suckers have been modified into hooks and the

tentacular In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

clubs—which are covered with many irregular rows of tiny suckers—may possess an enlarged central hook, with or without several smaller hooks. In the

magister armhook squid ''Berryteuthis magister'', also known as the magister armhook squid, commander squid or schoolmaster gonate squid, is a medium-sized squid in the family Gonatidae. It is found in cold, high latitude waters of the North Pacific where it is among ...

(''Berryteuthis magister''), only the females possess hooks. Species of the genus ''

'' differ from the rest of the family (and from most squid) by their lack of tentacles as adults. Only one species, the fiery armhook squid (''Gonatus pyros''), possesses

photophore A photophore is a glandular organ that appears as luminous spots on various marine animals, including fish and cephalopods. The organ can be simple, or as complex as the human eye; equipped with lenses, shutters, color filters and reflectors, ...

s; these are located on the ventral periphery of the eyes. Gonatids typically have muscular, cylindrical bodies with very soft, reddish to purplish-brown skin. The arms are thick and capable; the fins vary in shape and size, from sagittate and about 50% of the mantle length, to reniform and about 30% of the mantle length. Of moderate size, these squid range in size from 11 to 40 cm—most species are 25 cm or less. Females are somewhat larger than males.

Life history

These squid are

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...

, associated with the

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

and may roam as deep as 4,500 m or more, depending on the species. Their habits are poorly studied, but the squid are thought to undertake

diel Diel vertical migration (DVM), also known as diurnal vertical migration, is a pattern of movement used by some organisms, such as copepods, living in the ocean and in lakes. The word ''diel'' comes from the Latin ''dies'' day, and means a 24-ho ...

migration; by day, the squid remain in the blackness of the depths in midwater. By night, they ascend to the upper layers of the water column to feed by starlight. One species, however, '' Gonatopsis octopedatus'', has curiously recurved arms, suggesting a benthic existence. Little is known about the reproductive cycle of armhook squid. Most squid species whose reproduction has been observed have been seen to deposit eggs on the sea floor, then leave the eggs to hatch on their own. Five female ''Gonatus onyx'' squids have been observed in

Monterey Canyon Monterey Canyon, or Monterey Submarine Canyon, is a submarine canyon in Monterey Bay, California with steep canyon walls measuring a full 1 mile in height from bottom to top, which height/depth rivals the depth of the Grand Canyon itself. It is ...

dragging a membrane sack containing 2,000 to 3,000 developing eggs. It is uncertain if this behavior extends to other members of the family Gonatidae or if it is particular to this species. Prey items include both

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

and pelagic species, including smaller

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

, such as sculpins and juvenile

pollock Pollock or pollack (pronounced ) is the common name used for either of the two species of North Atlantic marine fish in the genus ''Pollachius''. '' Pollachius pollachius'' is referred to as pollock in North America, Ireland and the United Kingd ...

crustacean 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 group ...

s, including

euphausiid Krill are small crustaceans of the order Euphausiacea, and are found in all the world's oceans. The name "krill" comes from the Norwegian word ', meaning "small fry of fish", which is also often attributed to species of fish. Krill are consi ...

s and

amphipod Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far descr ...

s, and other squid.

Cannibalism Cannibalism is the act of consuming another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded in more than 1,500 species. Human cannibalism is well documented, b ...

is also known to occur among the Gonatidae.

Cetacean Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...

s are important predators of gonatids;

Baird's beaked whale Baird's beaked whale (''Berardius bairdii''), also known as the northern giant bottlenose whale, North Pacific bottlenose whale, giant four-toothed whale, northern four-toothed whale and the North Pacific four-toothed whale, is a species of whale ...

, the narwhal, the

short-finned pilot whale The short-finned pilot whale (''Globicephala macrorhynchus'') is one of the two species of cetaceans in the genus '' Globicephala'', which it shares with the long-finned pilot whale (''G. melas''). It is part of the oceanic dolphin family (Del ...

Dall's porpoise Dall's porpoise (''Phocoenoides dalli'') is a species of porpoise endemic to the North Pacific. It is the largest of porpoises and the only member of the genus ''Phocoenoides''. The species is named after American naturalist W. H. Dall. Taxono ...

, and

sperm whale The sperm whale or cachalot (''Physeter macrocephalus'') is the largest of the toothed whales and the largest toothed predator. It is the only living member of the genus ''Physeter'' and one of three extant species in the sperm whale famil ...

s are all known to feed upon them. Other predators include large

seabird 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 enviro ...

northern fur seal The northern fur seal (''Callorhinus ursinus'') is an eared seal found along the north Pacific Ocean, the Bering Sea, and the Sea of Okhotsk. It is the largest member of the fur seal subfamily (Arctocephalinae) and the only living species in t ...

elephant seal Elephant seals are very large, oceangoing earless seals in the genus ''Mirounga''. Both species, the northern elephant seal (''M. angustirostris'') and the southern elephant seal (''M. leonina''), were hunted to the brink of extinction for oi ...

s, and large fish, such as

grenadier A grenadier ( , ; derived from the word '' grenade'') was originally a specialist soldier who threw hand grenades in battle. The distinct combat function of the grenadier was established in the mid-17th century, when grenadiers were recruited fr ...

halibut Halibut is the common name for three flatfish in the genera '' Hippoglossus'' and ''Reinhardtius'' from the family of right-eye flounders and, in some regions, and less commonly, other species of large flatfish. The word is derived from ''h ...

and several species of

salmon Salmon () is the common name for several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the family (biology), family Salmonidae, which are native to tributary, tributaries of the ...

. In far southern waters,

Weddell seal The Weddell seal (''Leptonychotes weddellii'') is a relatively large and abundant true seal with a circumpolar distribution surrounding Antarctica. The Weddell seal was discovered and named in the 1820s during expeditions led by British sealing ...

s and

southern fur seal ''Arctocephalus forsteri'' (common names include the Australasian fur seal, South Australian fur seal, New Zealand fur seal, Antipodean fur seal, or long-nosed fur seal) is a species of fur seal found mainly around southern Australia and New Z ...

s, as well as several species of

albatross Albatrosses, of the biological family Diomedeidae, are large seabirds related to the procellariids, storm petrels, and diving petrels in the order Procellariiformes (the tubenoses). They range widely in the Southern Ocean and the North Pacifi ...

and

penguin Penguins (order (biology), order List of Sphenisciformes by population, Sphenisciformes , family (biology), family Spheniscidae ) are a group of Water bird, aquatic flightless birds. They live almost exclusively in the Southern Hemisphere: on ...

, feed upon '' Gonatus antarcticus''.

Species

*Genus '' Berryteuthis'' **''

Berryteuthis anonychus ''Berryteuthis anonychus'', also known as the minimal armhook squid or smallfin gonate squid, is a species of squid in the family Gonatidae. It is distinguished from other gonatids by the lack of hooks on all members, except for females on the ba ...

'', minimal armhook squid **''

Berryteuthis magister ''Berryteuthis magister'', also known as the magister armhook squid, commander squid or schoolmaster gonate squid, is a medium-sized squid in the family Gonatidae. It is found in cold, high latitude waters of the North Pacific where it is among ...

'' ***'' Berryteuthis magister magister'', magister armhook squid ***'' Berryteuthis magister nipponensis'' ***'' Berryteuthis magister shevtsovi'' *Genus '' Gonatopsis'' **Subgenus ''Boreoteuthis'' ***'' Gonatopsis borealis'', boreopacific armhook squid **Subgenus ''Gonatopsis'' ***'' Gonatopsis japonicus'' ***'' Gonatopsis makko'', Makko armhook squid ***'' Gonatopsis octopedatus'' ***''

'' * *Genus ''

'' **'' Gonatus antarcticus'' **'' Gonatus berryi'', Berry armhook squid **'' Gonatus californiensis'', California armhook squid **''

Gonatus fabricii ''Gonatus fabricii'', the Boreo-atlantic Armhook Squid, is a squid in the family Gonatidae. It occurs in the northern Atlantic Ocean from Canada to the Barents Sea. Until 1981, the name ''G. fabricii'' was usually misapplied to the very similar ...

'', boreoatlantic armhook squid **'' Gonatus kamtschaticus'' **'' Gonatus madokai'', Madokai armhook squid **'' Gonatus onyx'', clawed armhook squid or black-eyed squid **'' Gonatus oregonensis'', Oregon armhook squid **'' Gonatus pyros'', fiery armhook squid **''

Gonatus steenstrupi ''Gonatus'' is a genus of squid in the family Gonatidae The Gonatidae, also known as armhook squid, are a family of moderately sized squid. The family contains about 19 species in three genera, widely distributed and plentiful in cold boreal ...

'', Atlantic armhook squid **'' Gonatus ursabrunae'', brown bear armhook squid The species listed above with an asterisk (*) is questionable and needs further study to determine if it is a valid species or a synonym.

References

External links

Tree of Life web project: GonatidaeGonatidae discussion forum at TONMO.comSmall-clawed armhook quid subduing and killing an owlfish
video from the

Monterey Bay Aquarium Research Institute The Monterey Bay Aquarium Research Institute (MBARI) is a private, non-profit oceanographic research center in Moss Landing, California. MBARI was founded in 1987 by David Packard, and is primarily funded by the David and Lucile Packard Foundation ...

. * {{Taxonbar, from=Q656944 Squid Cephalopod families Taxa named by William Evans Hoyle