Seven-arm octopus

Seven-armed octopus
	Ventral view of young female (70 mm ML)
	Lateral view of young male
Conservation status
	; Least Concern (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Order:	Octopoda
Family:	Alloposidae; Verrill, 1881
Genus:	Haliphron; Steenstrup, 1861
Species:	H. atlanticus
Binomial name
	Haliphron atlanticus; Steenstrup, 1861[2]
Synonyms
	Alloposus mollis; Verrill, 1880; ?Octopus alberti; Joubin, 1895; Alloposus pacificus; Ijima & Ikeda, 1902; Heptapus danai; Joubin, 1929; Alloposus hardyi; Robson, 1930; ?Alloposina albatrossi; Robson, 1932;

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

Egg string and embryos of H. atlanticus collected north of the Cape Verde Islands (17°24′N 22°57′W / 17.400°N 22.950°W): The eggs measure around 8 mm at their widest.

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 / 38; -34. It is deposited at the University of Copenhagen Zoological Museum.^[5]

Since then, several specimens 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

Lower (left) and upper beaks of female Haliphron atlanticus (estimated 150 mm ML) in lateral view

3D red cyan glasses are recommended to view this image correctly.

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.
1 2 Julian Finn (2017). "Haliphron Steenstrup, 1859". World Register of Marine Species. Flanders Marine Institute. Retrieved 5 February 2018.
1 2 O'Shea, S. (2002). "Haliphron atlanticus — a giant gelatinous octopus" (PDF). Biodiversity Update. 5: 1.
1 2 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
1 2 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.
1 2 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.

External links

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.

[IUCN-1] 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.

[WoRMS-2] 1 2 Julian Finn (2017). "Haliphron Steenstrup, 1859". World Register of Marine Species. Flanders Marine Institute. Retrieved 5 February 2018.

[O'Shea2002-3] 1 2 O'Shea, S. (2002). "Haliphron atlanticus — a giant gelatinous octopus" (PDF). Biodiversity Update. 5: 1.

[O'Shea2004-4] 1 2 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.

[5] Current Classification of Recent Cephalopoda

[Rosaetal.2017-6] 1 2 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.

[Guerreiroetal.2015-7] 1 2 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.