''Brachioteuthis riisei'', also known as the common arm squid, is a species of

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 ...

in the family

Brachioteuthidae Brachioteuthidae is a family of squid containing two genera and around six species. Species *Genus ''Brachioteuthis'' **''Brachioteuthis beanii'' **''Brachioteuthis behnii'' **''Brachioteuthis bowmani'' * **''Brachioteuthis picta'', ornate arm ...

Description

This is a small species. It is almost colourless except for small chromatophores scarcely distributed. It has a long, thin, cylindrical mantle which grows to from 10 to 17 cm in length. The fin is approximately 35-50% of the length of the mantle. It has weak muscles, yet is nektonic.

Larval stage

The neck of the larvae is long. Their arms have two rows of suckers, with the having multiple rows of smaller suckers in the tentacular club at the proximal hub.

Distribution

This species is widely distributed and is native to many parts of the Atlantic and Pacific Oceans, and the Mediterranean and Black Seas. Except within the boreal Pacific Ocean, this is likely a cosmopolitan species.

Habitat and biology

Young animals live in the epi-

mesopelagic zone The mesopelagic zone (Greek μέσον, middle), also known as the middle pelagic or twilight zone, is the part of the pelagic zone that lies between the photic epipelagic and the aphotic bathypelagic zones. It is defined by light, and begins ...

, with adults occurring in the bathypelagic zone. ''Brachioteuthis riisei'' is an oceanic species which can be found over a wide range of depths from the surface to 3,000 m depth. Juvenile animals occur throughout the year which suggests that this species has an extended spawning season, although the juveniles reach peak abundance between May and August and in February in the North Atlantic while the peaks in the Mediterranean and off Northwest Africa are from April to July, in September, and from December to February. ''Brachioteuthis riisei'' is preyed upon by a range of marine mammals including Cuvier's beaked whale (''Ziphius cavirostris'') and striped dolphin (''Stenella coeruleoalba''), as well as by fish, for example the

blue shark The blue shark (''Prionace glauca''), also known as the great blue shark, is a species of requiem shark, in the family Carcharhinidae, which inhabits deep waters in the world's temperate and tropical oceans. Averaging around and preferring co ...

(''Prionace glauca'') and, in the Azores, the

swordfish Swordfish (''Xiphias gladius''), also known as broadbills in some countries, are large, highly migratory predatory fish characterized by a long, flat, pointed bill. They are a popular sport fish of the billfish category, though elusive. Swordfis ...

(''Xiphias gladius''), as well as by the

giant red shrimp ''Aristaeomorpha foliacea'', the giant red shrimp or giant gamba prawn, is a species of deep water benthopelagic decapod crustacean. It is found in all the world's oceans in the temperate and tropical zones. It is subject to some commercial fis ...

(''

Aristaeomorpha foliacea ''Aristaeomorpha foliacea'', the giant red shrimp or giant gamba prawn, is a species of deep water benthopelagic decapod crustacean. It is found in all the world's oceans in the temperate and tropical zones. It is subject to some commercial fis ...

'') in the

Sicilian Channel The Strait of Sicily (also known as Sicilian Strait, Sicilian Channel, Channel of Sicily, Sicilian Narrows and Pantelleria Channel; it, Canale di Sicilia or the Stretto di Sicilia; scn, Canali di Sicilia or Strittu di Sicilia, ar, مضيق ص ...

References

{{Taxonbar, from=Q2148844 Squid Molluscs described in 1882 Marine molluscs of Europe Cephalopods of Europe