|Giant Pacific octopus|
|E. dofleini observed off Point Piños, California, at a depth of 65 m|
|Distribution of E. dofleini|
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 m (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 lb) individual weighed live. The alternative contender is the seven-arm octopus (Haliphron atlanticus) based on a 61 kg (134 lb) carcass estimated to have a live mass of 75 kg (165 lb). However, a number of questionable size records would suggest E. dofleini is the largest of all octopus species by a considerable margin.
Size and description
E. dofleini is distinguished from other species by its sheer size. Adults usually weigh around 15 kg (33 lb), with an arm span of up to 4.3 m (14 ft). However, highly questionable records of specimens up to 272 kg (600 lb) in weight with a 9-m (30-ft) arm span have been reported. 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, an octopus can change the color of its skin, giving it the ability to blend into the environment. It is also able to alter its skin texture, providing even better camouflage. Dermal muscles in the octopus's skin can create a heavily textured look through papillation, or cause skin to appear smooth.
This species of octopus commonly preys upon shrimp, crabs, scallops, abalone, clams, lobsters, 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 four feet in length. Additionally, consumed carcasses of this same shark species have been found in giant Pacific octopus middens in the wild, providing strong evidence of these octopuses preying on small sharks in their natural habitat. In May 2012, amateur photographer Ginger Morneau was widely reported to have photographed a wild giant Pacific octopus attacking and drowning a seagull, which would demonstrate the species is not above eating any available source of protein within its size range, even birds.
Marine mammals, such as harbor seals, sea otters, and sperm whales, depend upon the giant Pacific octopus as a source of food. Pacific sleeper sharks are also confirmed predators of this species. In addition, the octopus is commercially fished in the United States.
Lifespan and reproduction
The giant Pacific octopus is considered to be short-lived for an animal of its size, with lifespans 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, which die protecting the eggs. Hatchlings are about the size of a grain of rice, and very few survive to adulthood.
Giant Pacific octopuses are semelparous; they are characterized by a single reproductive episode before death. After reproduction they enter a stage called senescence. This involves obvious changes in behaviour and appearance, including a reduced appetite, retraction of skin around the eyes giving them a more pronounced appearance, increased activity in uncoordinated patterns, and white lesions all over the body. While the duration of this stage is variable, it typically lasts about one to two months. Death is typically attributed to starvation as the females stop hunting and protect their eggs; males often spend more time in the open making them more likely to be preyed upon.
Octopuses are ranked as the most intelligent invertebrates. Giant Pacific octopuses are commonly kept on display at aquariums due to their size and interesting physiology, and have demonstrated the ability to recognize humans that they frequently come in contact with. These responses include jetting water, changing body texture, and other behaviors that are consistently demonstrated to specific individuals.
Very little is known about the population of this solitary creature, and it is not currently under the protection of CITES or evaluated in the IUCN Red List.
- 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.
- 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.
- O'Shea, S. (2002). "Haliphron atlanticus — a giant gelatinous octopus". Biodiversity Update 5: 1.
- Norman, M. 2000. Cephalopods: A World Guide. Hackenheim, ConchBooks, p. 214. ISBN 978-3-925919-32-9
- Smithsonian National Zoological Park: Giant Pacific Octopus
- High, W.L. 1976. The giant Pacific octopus. U.S. National Marine Fisheries Service, Marine Fisheries Review 38(9): 17-22.
- Mather, J. A.; Kuba, M. J. (2013). "The cephalopod specialties: Complex nervous system, learning, and cognition1". Canadian Journal of Zoology 91 (6): 431. doi:10.1139/cjz-2013-0009.
- "Octopus Eats Shark". Google Video. Retrieved 13 November 2012.
- Walla Walla University Marine Invertebrates Key: Giant Pacific Octopus
- McCulloch, S. 2012. B.C. woman nets fame for photos of octopus eating seagull. National Post, May 3, 2012.
- Sigler, M. F.; L. B. Hulbert, C. R. Lunsford, N. H. Thompson, K. Burek, G. O’Corry-Crowe, A. C. Hirons (24 Jul 2006). "Diet of Pacific sleeper shark, a potential Steller sea lion predator, in the north-east Pacific Ocean". Journal of Fish Biology (USA: Wiley-Blackwell) 69 (2): 392–405. doi:10.1111/j.1095-8649.2006.01096.x.
- Scheel, David. "Giant Octopus: Fact Sheet". Alaska Pacific University. Retrieved 13 November 2012.
- "Giant Pacific Octopus (Octopus dofleini)". NPCA. Archived from the original on 21 November 2008. Retrieved 13 November 2012.
- Anderson, R. C.; Wood, J. B.; Byrne, R. A. (2002). "Octopus Senescence: The Beginning of the End". Journal of Applied Animal Welfare Science 5 (4): 275–283. doi:10.1207/S15327604JAWS0504_02. PMID 16221078.
- Anderson, R. C. (2005). How smart are octopuses? Coral Magazine 2: 44–48.
- Anderson, R. C.; Mather, J. A.; Monette, M. Q.; Zimsen, S. R. M. (2010). "Octopuses (Enteroctopus dofleini) Recognize Individual Humans". Journal of Applied Animal Welfare Science 13 (3): 261–272. doi:10.1080/10888705.2010.483892. PMID 20563906.
|Wikimedia Commons has media related to Enteroctopus dofleini.|
- "CephBase: Enteroctopus dofleini". Archived from the original on 2005.
- Video of a giant octopus catching a shark
- Video of a giant pacific octopus in an aquarium