Seven-arm octopus
Seven-armed octopus | |
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Ventral view of young female (70 mm ML) | |
Lateral view of young male | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Mollusca |
Class: | Cephalopoda |
Order: | Octopoda |
Family: | Alloposidae Verrill, 1881 |
Genus: | Haliphron Steenstrup, 1861 |
Species: | H. atlanticus
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Binomial name | |
Haliphron atlanticus Steenstrup, 1861[2]
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Synonyms | |
The seven-arm octopus (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).[3][4] 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.[2]
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.[5]
Since then, several specimen have been caught throughout the Atlantic, as far as the Azores archipelago[6] and near South Georgia Island.[7]
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 (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.[3][4]
Ecology
Isotopic,[7] photographic and video evidence[6] have shown complex interactions between H.atlanticus and jellyfish and other gelatinous zooplankton, from feeding to protection, respectively.
Beak morphology
See also
References
- ^ Allcock, L. (2014). "Haliphron atlanticus". The IUCN Red List of Threatened Species. 2014: e.T163207A983527. doi:10.2305/IUCN.UK.2014-3.RLTS.T163207A983527.en. Downloaded on 05 February 2018.
- ^ a b Julian Finn (2017). "Haliphron Steenstrup, 1859". World Register of Marine Species. Flanders Marine Institute. Retrieved 5 February 2018.
- ^ 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.