Giant octopus

Taxobox
name = Giant octopuses

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image_caption = This close-up of "Enteroctopus dofleini" shows clearly the longitudinal folds on the body and paddle-like papillae that are diagnostic for this genus.
regnum = Animalia
phylum = Mollusca
classis = Cephalopoda
ordo = Octopoda
familia = Octopodidae
subfamilia = Octopodinae
genus = "Enteroctopus"
genus_authority = Rochebrune & Mabille, 1889
subdivision_ranks = Species
subdivision = See text.

"Enteroctopus" is an octopus genus, many of whose members are sometimes known as giant octopuses.

Description

"Enteroctopus" is a genus of generally temperate octopuses. Members of the genus "Enteroctopus" are characterized by their large size and are often known as the giant octopuses. "Enteroctopus" species have distinct longitudinal wrinkles or folds dorsally and laterally on the body. The head is distinctly narrower than the mantle width. The hectocotylus of the males in this genus, found on the third right arm, is long and narrow in comparison with other genera in the family Octopodidae, often comprising one fifth the length of the arm. Octopuses in this genus have large paddle-like e instead of the more conical papillae in other octopus genera.Hochberg, F.G. (1998). "Enteroctopus". In: "Taxonomic atlas of the benthic fauna of the Santa Maria Basin and the Western Santa Barbara Channel". Santa Barbara Museum of Natural History, Santa Barbara, California. p. 203.] Norman, M. (2003). "Cephalopods: A World Guide". ConchBooks: Heckenhaim, Germany. pp. 213–216.]

Type species

"Enteroctopus membranaceus" has often been regarded as type species of the genus, not because it was designated as such by Rochebrune and Mabille when they erected the genus, but because it was the the first named species in the genus. Robson in his 1929 monograph of octopods regarded "E. membranaceus" as a "species dubium" because the original description was insufficient to identify an individual species, the holotype was an immature specimen, and the type specimen was no longer extant. As such, the genus was considered invalid until Hochberg resurrected it in 1998. Hochberg noted that Robson had considered "E. membranaceus" a junior synonym of "E. megalocyathus", the second species assigned to the genus by Rochebrune and Mabille in their 1889 description. Additionally, since Rochebrune and Mabille did not actually assign type status to "E. membranaceus", Hochberg concluded that "Enteroctopus" was indeed a valid genus and transferred type species status to "E. megalocyathus" by virtual monotypy.

Distribution

Species in the genus "Enteroctopus" are restricted to the temperate areas of the Northern and Southern Hemispheres. "E. dofleini" is the only member of the genus found in the Northern Hemisphere and also the most widely distributed, occurring from San Diego, California along the North Pacific Rim to Japan, including the Okhotsk and Bering Seas. The other three species are found in the Southern Hemisphere; "E. megalocyathus" occurs on the southeastern coast of South America, [http://www.cephdev.utmb.edu/biogeo/eez.cfm?CephID=612 CephBase: Countries' Exclusive Economic Zones with "Enteroctopus megalocyathus"] ] "E. magnificus" on the southwestern coast of Africa from Namibia to Port Elizabeth, South Africa, and "E. zealandicus" in temperate New Zealand.

Size

The member of this genus that best embodies the common name "Giant Octopus" is "Enteroctopus dofleini", which holds the record of being the world's largest octopus based on direct measurements of a 71 kg (156.5 lb) individual weighed live. [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.] This octopus had a total length of 7 m (23 ft). The remaining members of the genus are substantially smaller, with "E. megalocyathus" having an average mass of 4 kg and reaching a total length of 1 m.Perez, M.C., D.A. Lopez, K. Aguila and M.L. Gonzalez (2006). Feeding and growth in captivity of the octopus "Enteroctopus megalocyathus" Gould, 1852. "Aquaculture Research" 37: 550–555.] [Gleadall, I.G. and M.A. Salcedo-Vargas (2004). Catalogue of the Cephalopoda Specimens in the Zoology Department of Tokyo University Museum. "Interdisciplinary Information Sciences" 10: 113–142.] "E. magnificus" reaches a total length of around 1.5 m.

Species

* Genus "Enteroctopus"Norman, M.D. & F.G. Hochberg (2005). The current state of octopus taxonomy. "Phuket Marine Biological Center Research Bulletin" 66: 127–154.]
** North Pacific Giant Octopus, "Enteroctopus dofleini"
** Southern Giant Octopus, "Enteroctopus magnificus"
** "Enteroctopus megalocyathus"
** "Enteroctopus zealandicus"

ee also

*Giant squid
*Colossal Squid
*Cephalopod size
*Kraken

References