Scientific name Haliphron atlanticus Higher classification Haliphron Order Octopus | Superfamily Argonautoida Rank Species | |
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Family AlloposidaeVerrill, 1881 Genus HaliphronSteenstrup, 1861 Similar Octopus, Cephalopod, Ocythoe tuberculata, Incirrina, Argonautidae | ||
The seven-arm octopus or septipus (Haliphron atlanticus) 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 (11 ft) and mass of 75 kg (165 lb). The only other similarly large extant species is the giant Pacific octopus, Enteroctopus dofleini.
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The genera Alloposina Grimpe, 1922, Alloposus Verrill, 1880 and Heptapus Joubin, 1929 are junior synonyms of Haliphron.
Description
The seven-arm octopus is so named because in males the hectocotylus (a specially modified arm used in egg fertilization) 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 38°N 34°W. It is deposited at the Zoologisk Museum, University of Copenhagen.
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 octopodes, was the first validated record of Haliphron from the South Pacific. It had a mantle length of 0.69 m (2.3 ft), a total length of 2.90 m (9.5 ft), and a weight of 61.0 kg (134.5 lb), although it was incomplete.