Seven-armed octopus

Haliphron atlanticus

The seven-arm octopus is one of the two largest known species of octopus; based on scientific records, it has a maximum estimated total length of 3.5 m and mass of 75 kg . The only other similarly large extant species is the giant Pacific octopus, ''Enteroctopus dofleini''.

The genera ''Alloposina'' Grimpe, 1922, ''Alloposus'' Verrill, 1880 and ''Heptapus'' Joubin, 1929 are junior synonyms of ''Haliphron'', a monotypic genus in the monotypic family Alloposidae, part of the superfamily Argonautoidea in the suborder Incirrata of the order Octopoda.
Seven Arm Octopus (Haliphron atlanticus) trawled from between 1,500 meters depth and the surface, Gulf of Mexico, July 2018.  Part of the DEEPEND project.  Deep Sea,Haliphron atlanticus,Life in the dark,Seven-armed octopus

Appearance

The seven-arm octopus is so named because in males, the hectocotylus is coiled in a sac beneath the right eye. Due to this species' thick, gelatinous tissue, the arm is easily overlooked, giving the appearance of just seven arms. However, like other octopuses, it actually has eight.

Distribution

The type specimen of ''H. atlanticus'' was collected in the Atlantic Ocean at . It is deposited at the University of Copenhagen Zoological Museum.

Since then, several specimens have been caught throughout the Atlantic, as far as the Azores archipelago and near South Georgia Island.

In 2002, a single specimen of giant proportions was caught by fishermen trawling at a depth of 920 m off the eastern Chatham Rise, New Zealand. This specimen, the largest of this species and of all octopuses, was the first validated record of ''Haliphron'' from the South Pacific. It had a mantle length of 0.69 m , a total length of 2.90 m , and a weight of 61.0 kg , although it was incomplete.

Habitat

Isotopic, photographic and video evidence have shown complex interactions between ''H.atlanticus'' and jellyfish and other gelatinous zooplankton, from feeding to protection, respectively.

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Status: Least concern
EX EW CR EN VU NT LC
Taxonomy
KingdomAnimalia
DivisionMollusca
ClassCephalopoda
OrderOctopoda
FamilyAlloposidae
GenusHaliphron
SpeciesH. atlanticus