Enteroctopus dofleini

Giant Pacific Octopus
E. dofleini observed off Point Piños, California, at a depth of 65 meters.
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Order:	Octopoda
Family:	Octopodidae
Genus:	Enteroctopus
Species:	E. dofleini
Binomial name
Enteroctopus dofleini (Wülker, 1910)
Distribution of E. dofleini
Synonyms
Octopus punctatus Gabb, 1862 Octopus dofleini Wülker, 1910 Polypus dofleini Wülker, 1910 Octopus dofleini dofleini (Wülker, 1910) Polypus apollyon Berry, 1912 Octopus dofleini apollyon (Berry, 1912) Polypus gilbertianus Berry, 1912 Octopus gilbertianus Berry, 1912 Octopus apollyon (Berry, 1913) Octopus madokai Berry, 1921 Paroctopus asper Akimushkin, 1963 Octopus dofleini martini Pickford, 1964

Enteroctopus dofleini, also known as the Giant Pacific Octopus or North Pacific Giant Octopus, is a large cephalopod belonging to the genus Enteroctopus. It can be found in the coastal North Pacific, usually at a depth of around 65 meters (215 ft). It can, however, live in much shallower or much deeper waters. It is arguably the largest octopus species, based on a scientific record of a 71 kg (156.5 lb) individual weighed live.^[1] The alternative contender is the Seven-arm Octopus based on a 61 kg (134 lb) carcass estimated to have a live mass of 75 kg (165 lb).^[2][3] However, there are a number of questionable size records that would suggest E. dofleini is the largest of all octopus species by a considerable margin.^[4]

Size and description

Close-up of E. dofleini showing the longitudinal folds on the body and the paddle-like papillae.

The Giant Pacific Octopus, are distinguished from other species by their sheer size. Adults usually weigh around 15 kg (33 lb), with an arm span of up to 4.3 m (14 ft).^[5] However, there are highly questionable records of specimens up to 272 kg (600 lb) in weight with a 9 m (30 ft) arm span.^[6] The mantle of the octopus is spherical in shape and contains most of the animal's major organs. By contracting or expanding tiny pigment-containing granules within cells known as chromatophores in its tissue, an octopus can change the color of its skin, giving it the ability to blend in to the environment.

Diet

This species of octopus commonly preys upon shrimp, crabs, scallops, abalone, clams, and fish. Food is procured with its suckers and then crushed using its tough "beak" of chitin. They have also been observed in captivity catching Spiny dogfish (Squalus acanthias) of up to 3-4 feet in length.^[7] Additionally, consumed carcasses of this same shark species have been found in Giant Pacific Octopus middens in the wild, providing strong evidence that these octopuses prey on sharks in their natural habitat. ^[8]

Predators

Marine mammals such as Harbor Seals, Sea Otters, and Sperm Whales depend upon the Giant Pacific Octopus as a source of food. The octopus is also commercially fished in the United States.

Life span and reproduction

The Giant Pacific Octopus is considered to be short-lived for an animal its size, with life spans that average only 3-5 years in the wild. To make up for its relatively short life span, the octopus is extremely prolific. It can lay up to 100,000 eggs which are intensively cared for by the females, who die protecting the eggs. Hatchlings are about the size of a grain of rice, and very few survive to adulthood.

During reproduction, the male octopus deposits a spermatophore (or sperm packet) more than 1 meter long. Large spermatophores are characteristic of octopuses in this genus.^[4]

Conservation

Very little is known about the population of this solitary creature and the Giant Pacific Octopus is not currently under the protection of CITES or evaluated in the IUCN Red List.

See also

• Octopus wrestling
• Cephalopod size

References

1. ^ Cosgrove, J.A. 1987. Aspects of the Natural History of Octopus dofleini, the Giant Pacific Octopus. M.Sc. Thesis. Department of Biology, University of Victoria (Canada), 101 pp.
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.
3. ^ O'Shea, S. 2002. Haliphron atlanticus — a giant gelatinous octopus. Biodiversity Update 5: 1.
4. ^ ^{a b} Norman, M. 2000. Cephalopods: A World Guide. Hackenheim, ConchBooks, p. 214.
5. ^ Smithsonian National Zoological Park: Giant Pacific Octopus
6. ^ High, W.L. 1976. The giant Pacific octopus. U.S. National Marine Fisheries Service, Marine Fisheries Review 38(9): 17-22.
7. ^ http://video.google.com/videoplay?docid=-7004909622962894202
8. ^ Walla Walla University Marine Invertebrates Key: Giant Pacific Octopus

• Giant Pacific Octopus
• Giant Pacific Octopus: Fact Sheet

External links

• CephBase: Enteroctopus dofleini
• Video of a giant octopus catching a shark
• Video of a giant pacific octopus in an aquarium