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).[1][2] The only other similarly large extant species is the giant Pacific octopus, Enteroctopus dofleini.
| Seven-armed octopus | |
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| Ventral view of young female (70 mm ML) | |
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| Lateral view of young male | |
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| Family: | Alloposidae Verrill, 1881
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| Genus: | Haliphron Steenstrup, 1861
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| Species: | H. atlanticus
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| Binomial name | |
| Haliphron atlanticus Steenstrup, 1861
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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 / 38°N 34°W. It is deposited at the University of Copenhagen Zoological Museum.[3]
Since then, several specimen have been caught throughout the Atlantic, as far as the Azores arquipelago[4] and near South Georgia Island[5].
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.[1][2]
Ecology
Isotopic[5], photographic and video evidence [4] have shown complex interaction between H.atlanticus and jellyfish and other gelatinous zooplancton, from feeding to protection (respectively).
Beak morphology
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3D red cyan glasses are recommended to view this image correctly.See also
References
- ^ a b O'Shea, S. (2002). "Haliphron atlanticus — a giant gelatinous octopus" (PDF). Biodiversity Update. 5: 1.
- ^ a b O'Shea, S. (2004). "The giant octopus Haliphron atlanticus (Mollusca : Octopoda) in New Zealand waters". New Zealand Journal of Zoology. 31 (1): 7–13. doi:10.1080/03014223.2004.9518353.
- ^ Current Classification of Recent Cephalopoda
- ^ a b Rosa, R.; Kelly, J.; Lopes, V.; Paula, J.; Goncalves, J.; Calado, R.; Norman, M.; Barreiros, J. (2017). "Deep-sea seven-arm octopus hijacks jellyfish in shallow waters". Marine Biodiversity. doi:10.1007/s12526-017-0767-3.
- ^ a b Guerreiro, M.; Phillips, R.; Cherel, Y.; Ceia, F.; Alvito, P.; Rosa, R.; Xavier, J. (2015). "Habitat and trophic ecology of Southern Ocean cephalopods from stable isotope analyses" (PDF). Marine Ecology Progress Series. 530: 119–134. doi:10.3354/meps11266.
Further reading
- Bakken, T. & T. Holthe 2002. Haliphron atlanticum (Cephalopoda, Alloposidae) caught in Skorafjorden (64°N), Norway. Fauna norv. 22: 37-38.
- Willassen, E. 1986. Haliphron atlanticus Steenstrup (Cephalopoda: Octopoda) from the coast of Norway. Sarsia 71: 35-40.
External links
- "CephBase: Seven-arm octopus". Archived from the original on 2005-08-17.
- Tree of Life web project: Haliphron atlanticus
- The giant octopus Haliphron atlanticus (Mollusca: Octopoda) in New Zealand waters
- BBC News: Giant octopus puzzles scientists
- Tony Wu Underwater Photography: Seven-arm octopus
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