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Seven Arm Octopus

Haliphron atlanticus Steenstrup 1861

Comprehensive Description

provided by Smithsonian Contributions to Zoology
Alloposus mollis Verrill, 1880

DESCRIPTION.—The mantle is short, gelatinous, and broad (length is nearly equal to width). The mantle opening is wide and reaches roughly to the level of the dorsal edge of the eyes. On the inner surface of the mantle, just medial to the gills and lateral to the median pallial adductor muscle is a distinct transverse fold of the mantle which forms a deep groove. This is the mantle component of the funnel-mantle locking mechanism.

The funnel is very large. It extends far past the eyes and past bases of the ventral arms. Except for a short free tip, it is completely embedded in the gelatinous tissue of the head. The funnel organ is large and W-shape. The posterior lateral edges of the funnel, near the point of attachment of the funnel retractor muscles, fold sharply forward to form the funnel component of the funnel-mantle locking mechanism.

The head is broad and bears large eyes. There is no lateral or dorsal constriction between the mantle and head. Posterior to each eye lies a low, flattened knob which is the “olfactory” organ.

The arms are very large, but gelatinous. They are in the order of I>II>III>IV. The suckers begin in a single but slightly irregular series near the base of each arm and gradually become biserially arranged proximal to the edge of the web.

The gills are huge and bear 18 lamellae, each of which is robust and highly folded. The body wall which covers the ventral surface of the viscera is surprisingly tough and opaque. Very small nephridial papillae project from near the base of the gills. Posterior and lateral to the large median pallial adductor muscle, a pair of oviducts opens through prominent papillae. Each papilla is extremely large and muscular. The largest eggs in the ovary are about 1.5 mm long by 0.5 mm wide. The viscera are essentially as illustrated by Thore (1949). The kidneys are very large and extend to the posterior end of the visceral mass. The crop is situated dorsal to the liver, and the stomach and caecum are dorsal and partially posterior to the liver. The entire dorsal surface of the visceral mass is free from the overlying mantle. The space between the visceral mass and the mantle communicates with the ventral mantle cavity laterally around the visceral mass anterior to the funnel-retractor muscles.

The rachidian tooth of the radula is tricuspid; the first lateral is small and bicuspid, and the second and third laterals are unicuspid. The marginals are simple and broad.

The data for the single specimen captured are: Sex, ; M.L., 115 mm; M.W., 126 mm; H.W., 120 mm; Arm L., I–IV, respectively, 360 mm, 260 mm, 240 mm, 200 mm; Eye D., 38 mm.

TYPE LOCALITY.—South of Newport, Rhode Island, western north Atlantic.

LOCATION OF TYPE.—United States National Museum.
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bibliographic citation
Young, Richard E. 1972. "The systematics and areal distribution of pelagic cephalopods from the seas off Southern California." Smithsonian Contributions to Zoology. 1-159. https://doi.org/10.5479/si.00810282.97

Seven-arm octopus

provided by wikipedia EN

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 Heptopus 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

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Egg string and embryos of H. atlanticus collected north of the Cape Verde Islands (): 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 (west of the Azores). 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.

Predators of H. atlanticus include the blue shark, Hawaiian monk seal, sperm whale, and swordfish.[8][9][10][11][12]

Beak morphology

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Lower (left) and upper beaks of female Haliphron atlanticus (estimated 150 mm ML) in lateral view
3d glasses red cyan.svg 3D red cyan glasses are recommended to view this image correctly.

See also

References

  1. ^ Allcock, L. (2014). "Haliphron atlanticus". IUCN Red List of Threatened Species. IUCN. 2014: e.T163207A983527. doi:10.2305/IUCN.UK.2014-3.RLTS.T163207A983527.en. Downloaded on 05 February 2018.
  2. ^ a b Julian Finn (2017). "Haliphron Steenstrup, 1859". World Register of Marine Species. Flanders Marine Institute. Retrieved 5 February 2018.
  3. ^ a b O'Shea, S. (2002). "Haliphron atlanticus — a giant gelatinous octopus" (PDF). Biodiversity Update. 5: 1.
  4. ^ 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.
  5. ^ Current Classification of Recent Cephalopoda
  6. ^ 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. 49: 495–499. doi:10.1007/s12526-017-0767-3.
  7. ^ 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. Bibcode:2015MEPS..530..119G. doi:10.3354/meps11266.
  8. ^ Henderson, A. C.; Flannery, K.; Dunne, J. (May 2001). "Observations on the biology and ecology of the blue shark in the North-east Atlantic". Journal of Fish Biology. 58 (5): 1347–1358. doi:10.1111/j.1095-8649.2001.tb02291.x.
  9. ^ Goodman-Lowe, G. D. (29 October 1998). "Diet of the Hawaiian monk seal (Monachus schauinslandi) from the Northwestern Hawaiian islands during 1991 to 1994". Marine Biology. 132 (3): 535–546. doi:10.1007/s002270050419.
  10. ^ Chua, Marcus A.H.; Lane, David J.W.; Ooi, Seng Keat; Tay, Serene H.X.; Kubodera, Tsunemi (5 April 2019). "Diet and mitochondrial DNA haplotype of a sperm whale (Physeter macrocephalus) found dead off Jurong Island, Singapore". PeerJ. 7: e6705. doi:10.7717/peerj.6705. PMC 6452849. PMID 30984481.
  11. ^ Clarke, M.R.; Pascoe, P.L. (11 May 2009). "Cephalopod Species in the Diet of a Sperm Whale (Physeter Catodon) Stranded at Penzance, Cornwall". Journal of the Marine Biological Association of the United Kingdom. 77 (4): 1255. doi:10.1017/S0025315400038819.
  12. ^ Chancollon, Odile; Pusineri, Claire; Ridoux, Vincent (1 September 2006). "Food and feeding ecology of Northeast Atlantic swordfish ( Xiphias gladius ) off the Bay of Biscay". ICES Journal of Marine Science. 63 (6): 1075–1085. doi:10.1016/j.icesjms.2006.03.013.
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Seven-arm octopus: Brief Summary

provided by wikipedia EN

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). The only other similarly large extant species is the giant Pacific octopus, Enteroctopus dofleini.

The genera Alloposina Grimpe, 1922, Alloposus Verrill, 1880 and Heptopus 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.

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