''Gonatopsis okutanii'' is a species of squid from the

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

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 waters of the Pacific Ocean. At least one species is known f ...

from the northern Pacific Ocean. It is of uncertain taxonomic status, the presence of remnant

tentacles 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 mainl ...

on spent females indicate that this species does not belong in the genus '' Gonatopsis'' and the differences between this species and '' Gonatus makodai'' have led to some authorities stating that ''G. okutanii'' is a junior synonym of ''Eogonatus tinro''. However the

World Register of Marine Species The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive list of names of marine organisms. Content The content of the registry is edited and maintained by scientific specialis ...

still recognises ''Gonatopsis okutanii'' as the valid name for this taxon.

Description

''Gonatopsis okutanii'' is a medium-sized species of squid with a gelatinous body, 5 teeth on the radula and long, thin

arms Arms or ARMS may refer to: *Arm or arms, the upper limbs of the body Arm, Arms, or ARMS may also refer to: People * Ida A. T. Arms (1856–1931), American missionary-educator, temperance leader Coat of arms or weapons *Armaments or weapons **Fi ...

. Arms II & III are very long and slender; and their length is at least equal to the mantle length. The arms have thick bases but become weak and narrow towards their tips. Arms I-III have 2 rows of hooks in the middle and 2 rows of small suckers while arm IV only has suckers. All the arms have 5-10 pairs of medial hooks or suckers which are spaced wide apart, the arm suckers have 7-9 teeth placed on the distal edge of their ring. All known specimens are spent females which have short, remnants of tentacles situated between the proximal ends of arms III and IV. They have very large eyes, a buccal membrane which has 7 lappets and there is in

nuchal crest The nuchal lines are four curved lines on the external surface of the occipital bone: * The upper, often faintly marked, is named the highest nuchal line, but is sometimes referred to as the Mempin line or linea suprema, and it attaches to the epi ...

which has three or four indistinct nuchal folds on either side along its length. The radula has teeth in five transverse rows. The mantle is thick, soft, gelatinous and conical in shape with a mantle length which varies between 18 cm and 25 cm. The skin is dark purple in colour marked with "eye patches". It has short rhomboid shaped, narrow fins and a short tail. Tentacles are present on the subadult specimens described as ''Eogonatus tinro'' and these have a

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 ...

lacking any hooks and with equal sized suckers arranged in numerous irregular rows.

Distribution

''Gonatopsis okutanii'' occurs in the North Pacific Ocean from Japan in the east to

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and Canada in the west.

Habitat and biology

''Gonatopsis okutanii'' is reported to have relatively large eggs up to 2.3 mm in length, compared to female body size. The male and female appear to copulate "head to head", and the adult females do not appear to die after their first breeding. They are caught at intermediate depths and spent females have been collected at depths of between 525m and 550 m and have been found in the stomachs of sperm whales.

Naming

Some authorities treat ''Gonatopsis okutanii'' as a junior synonym of ''Eogonatus tinro'' and the two taxa were described in the same paper by Kir Nesis, ''G. okutanii'' was based on spent females, while ''E. tinro'' was based on young squid, however ''E. tinro'' has priority.

References

{{Taxonbar, from=Q2322172 Squid Molluscs described in 1972