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.

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.. more