Learn About Octopuses & Relatives

For reasons of large body size, fast-moving predatory activities, large beak, relatively large brain, and an eye structure similar to that of humans, cephalopods rank among the most interesting of all marine invertebrates. A considerable mythology has developed around them. The first authentic photos of a living giant squid Architeuthis were obtained only in 2005, and there are reports of even larger deep sea-inhabiting squid species. Only 2 octopus species are commonly encountered on the northern parts of the west coast, the giant octopus1 Enteroctopus dofleini and the smaller Octopus rubescens. Two other species2, Octopus bimaculoides and O. bimaculatus, occur only in southern California and Baja California. Their distributions overlap but little is known of their ecological relationships. Several species of squids inhabit, or regularly visit or wash up on, west-coast shores, including the shallow-water Rossia pacifica, the oceanic squid Doryteuthis (Loligo) opalescens, and the deep-dwelling giant squid Moroteuthis robustus. An increasingly common visitor to west-coast shores, including British Columbia and southern Alaska in summer and early autumn, is the feisty Humboldt squid Dosidicus gigas3, which likely follows incursions of warm-water northwards. Modest fisheries for giant octopuses Enteroctopus dofleini exists in Alaska (landings of about 200 metric tonnes annually) and Queen Charlotte Islands, British Columbia.Capture of squids Doryteuthis opalescens represents the largest fishery in California, with over 100,000 metric tonnes being harvested annually. Cosgrove & Sendall Unpubl MS from RBC Museum, Victoria, British Columbia.

photograph of giant squid Moroteuthis robusta caught by fishers off the coast of Vancouver Island, British ColumbiaGiant squid Moroteuthis robusta caught in a trawl net off the coast of Vancouver Island, British Columbia

NOTE1 how “giant” is Enteroctopus dofleini? Specimens up to 40kg are commonly caught. The largest individual recorded anecdotally from northern British Columbia weighed in at 270kg with a tentacle spread of 9.7m. High 1976 Mar Fish Rev 38: 17.

photograph of 2 post-reproductive and dying Humboldt squids Dosidicus gigas in Baja CaliforniaTwo post-reproductive and moribund male Humboldt squids Dosidicus gigas in Baja California being collected as food for captive green turtles (usually thought of as being seagrass-eaters)

NOTE2 how related are the west-coast species? This is investigated for the 4 species mentioned here, with the addition of a deep-water Californian species Octopus californicus, by researchers at Simon Fraser University, BC. DNA-sequencing results suggest that O. bimaculoides and O. bimaculatus form their own clade, separate from a clade containing Enteroctopus dolfleini and O. californicus. Octopus rubescens is separate from the others, but possibly more closely aligned with the southern California group. Sosa et al. 1995 Mol Phylogenetics & Evol 4 (2): 163.

NOTE3 up to a decade ago sightings of Humboldt squids were mostly restricted to Mexico and southern California. However, since summer 2009 they have been seen on the west coast of Vancouver Island, BC and also in Alaskan waters. Researchers at DFO, BC have recently attached telemetry devices to specimens caught off Vancouver Island, so further information on their movements may be forthcoming

In addition to the 2 northern octopus species mentioned above (E. dolfleini and O. rubescens), researchers from Alaska Pacific University, Anchorage have described a second large octopus similar to Enteroctopus dofleini. Specimens of this new species are commonly caught in drag trawls and have probably been mistaken for E. dofleini for many decades. The new species has several morphological features separating it from E. dolfleini, including the presence of lateral mantle frills and absence of longitudinal mantle folds (see photographs). Additionally, the new species has characteristic texturing of the mantle below the frill and lacks “horns” or papillae above the eyes. These features don’t seem like much of a difference, but genetic analyses (nucleotide sequences from microsatellites and a portion of the OCDE gene) done by the authors on skin swabs of the two morphs provide evidence for the presence of a novel sister clad that they call the frilled giant Pacific octopus, Enteroctopus n. sp. Of 21 octopuses examined by the researchers from shrimp-pot by-catch, two-thirds are E. dolfleini, while one-third is the novel morph. Hollenbeck & Scheel 2017 Amer Malacol Bull 35 (2): 134. Photographs courtesy the authors.

comparison photographs of a new species of giant octopus Enteroctopus n sp. from Alaska
Enterotopus n.sp. Note lateral mantle frill and papillae or “horns” above the eyes.
Enteroctopus dolfleini. Note skin folds on ventral mantle and absence of papillae above the eyes. Other differences are discussed by the authors

ANIMATION of snail meeting OCTOPUS
© 2010 Thomas Carefoot

To learn about west-coast OCTOPUSES & RELATIVES: select a topic from the Mollusca > Octopuses & relatives menu at the top of the page

OR: play the ANIMATION of the snail meeting the OCTOPUS

OR, if you want to see other animations: follow the snail on its ODYSSEY by CLICKING on any X-marked invertebrate on the map

Phylum Mollusca (lit. “soft” or “shellfish” L.)

Class Cephalopoda (lit. “head foot” G.), referring to the body structure of head lying directly overtop of the muscular foot (in cephalopods, the ancestral foot evolved into arms and tentacles)

SubClass Coleoidea (lit. “sheath” G.), including octopuses and squids

Order Sepiolioidea (lit. “cuttlefish” G.), including the stubby squid Rossia pacifica

Order Teuthoidea (lit. “squid” G.), including several species of squids: Doryteuthis opalescens, the giant squid Moroteuthis (Onykia) robustus (4m in total length), the Humboldt squid, Dosidicus gigas, and the stubby squid Rossia pacifica (a small bottom-inhabiting species)

Order Octopoda (lit. “eight arms” L.), including the octopuses Enteroctopus dofleini, Octopus rubescens, O. bimaculatus and O. bimaculoides (the last 2 in California only)

NOTE: Onykia robusta is smaller than Moroteuthis robusta and differs morphologically from the latter in only minor ways. Recent molecular evidence suggests that the smaller form may be justan immature stage of the larger, and the suggestion by the authors of this latest study is that the species be known as Onykia robusta. However, until this change is commonly adopted, this squid species will be referred to in the Odyssey by the species name used by a particular author. Wakabayashi et al. 2007 J Mar Biol Ass UK 87 (4): 959.