Octopus bimaculatus

Geographic Range

Octopus bimaculatus is found off the coast of Northern California south to Baja California, Mexico. There are many observations recorded from the Channel Islands as well.

• Biogeographic Regions
• pacific ocean pacific ocean
  • native native

Habitat

Octopus bimaculatus inhabits rocky reefs in subtidal and intertidal habitats to a depth of 15 m. It prefers to den in abandoned man-made piping or small holes in canyon ledges.

• Habitat Regions
• temperate temperate
• saltwater or marine saltwater or marine

• Aquatic Biomes
• benthic benthic
• reef reef
• coastal coastal

• Other Habitat Features
• intertidal or littoral intertidal or littoral

Physical Description

The California two-spot octopus is usually light brown or mottled in coloration, with two characteristic spots under each eye, hence its name. Its mantle, located in the center of eight tentacles, is pear-shaped with a beak and mouth in the middle. Each of its tentacles grow to a few feet in length, a little more than half of its body size. Its tentacles are each adorned with suction cups used for grasping and holding prey as well as for taste. The octopus can grow to about 18 inches long when fully mature. Like its relatives, Octopus bimaculatus can use the chromatophores in its skin to change its color and texture when hunting for prey or hiding from predators. Octopus bimaculoides is another species of octopus that has the same common name as Octopus bimaculatus because they look so similar, but it is important to know that they are two different species.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Development

Octopus bimaculatus grows and matures quickly due to its short life span of one to two years. When in the embryo stage, it goes through two different stages of growth: a rapid initial stage and a slower phase in which its beaks, shells, and brain tissue begins to develop. Each individual octopus develops and matures at their own individual rate, resulting in varying growth factors. Once hatched, the young octopuses are completely independent and ready to catch their own prey. Once they reach one to two years of age, they are ready to reproduce.

• Development - Life Cycle
• indeterminate growth indeterminate growth

Reproduction

Octopus bimaculatus can reproduce at any time during the year, but most commonly when the water warms during the summer months. The male octopus will use his spermatophores to inseminate the female; the male will die shortly after.

• Mating System
• monogamous monogamous

After fertilization, the female will create a den and seal herself in to lay her eggs. A single female can lay thousands of eggs. She will care for her eggs by blowing cool water over them from her siphon to keep them oxygenated. During the process of caring for her eggs, the female often expires due to starvation and exhaustion. After the eggs hatch, which may take 150 to 210 days, the mother will leave the den if she survives and the larval octopus will drift with the tide before settling on the ground to begin developing.

• Key Reproductive Features
• semelparous semelparous
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous

Males die shortly after mating. Females, however, exhibit significant parental care. They remain with the eggs after they are laid, protecting them and siphoning cool water over them. During this time, females do not feed and often die from starvation and exhaustion. Once the eggs hatch, the larvae are independent.

• Parental Investment
• female parental care female parental care
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

Octopus bimaculatus lives between 12 to 18 months in the wild, while some kept as pets have been known to live for up to 2 years.

Behavior

Many species of octopus are mainly active at night, and the California two spotted octopus is no exception. Octopus bimaculatus leaves the den at night to hunt and mate. Its highly developed eyes make nocturnal behavior possible. Individuals range widely, searching for food, and find temporary burrows for shelter when not hunting. They do not often return to their previous dens and will never construct one of their own. Octopuses will compete for dens, chasing conspecifics out of a den that they desire. They will bring their prey to their dens to consume, creating "middens" of various bivalve shells, crab claws, and other hard parts of their invertebrate prey.

• Key Behaviors
• natatorial natatorial
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• solitary solitary
• territorial territorial

Communication and Perception

Octopus bimaculatus and other cephalopods communicate visually. They manipulate the chromatophores on their bodies to display various signals to conspecifics and to predators as warning signs. They have highly developed eyes. Common visual cues and signs are used to indicate that they are ready to mate, have already mated, are not interested, are expressing dominance, or show relationship to other individuals. Though O. bimaculatus is a solitary creature, it will alert conspecifics to predators or prey in the area.

• Communication Channels
• visual visual
• tactile tactile

• Other Communication Modes
• mimicry mimicry

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• vibrations vibrations
• chemical chemical

Food Habits

The main source of food for Octopus bimaculatus is snails, crustaceans, bivalves, and limpets. An octopus may hunt for its prey, or it may lie in wait for food to swim or crawl by its hiding place, while it remains camouflaged in the rocks. Once Octopus bimaculatus has captured its prey with its tentacles, it uses its suckers to hold onto the prey while it is moved towards the beak and radula. The radula can pierce the thick shells of other mollusks and inject a toxin that will affect the prey's nervous system. The beak tears soft tissue, and the radula is then used to scrape the flesh into shreds for consumption.

• Primary Diet
• carnivore carnivore
  • molluscivore molluscivore

• Animal Foods
• fish
• mollusks
• aquatic crustaceans

Predation

Predators of Octopus bimaculatus include moray eels, sea lions, harbor seals, and humans. To scare off predators, O. bimaculatus can change its skin by manipulating its chromatophores and flashing warning signals.

• Anti-predator Adaptations
• mimic
• cryptic cryptic

Ecosystem Roles

California two-spot octopuses are both primary and secondary consumers. They help maintain the population of smaller mollusks as well as serve as food for larger predatory animals. They are also known to be hosts for ectoparasitic flagellates and ciliate protozoans, which live on the octopuses' gills.

Economic Importance for Humans: Positive

This species of octopus is not hunted by humans as a main source of food, however it is caught in traps and nets and can be sold. As of 2013 in California, the daily bag limit is 35 specimens, and there are no size limits. There is a market in the pet supply trade. Because two spotted octopuses are small (up to 45 cm), they are welcome aquarium pets. Aquarium websites list them from US $30 to $40 depending on size.

• Positive Impacts
• pet trade pet trade
• food food

Economic Importance for Humans: Negative

There are no known adverse effects of Octopus bimaculatus on humans.

Conservation Status

Octopus bimaculatus has no special conservation status.

Additional Links

Encyclopedia of Life

Contributors

Brittany Hamilton (author), San Diego Mesa College, Lauren Swope (author), San Diego Mesa College, Paul Detwiler (editor), San Diego Mesa College, Angela Miner (editor), Animal Diversity Web Staff.

References

Anderson, R., W. James. 2004. Interspecific Evaluation of Octopus. Journal of Applied Animal Welfare Science , 7: 95–106. Accessed February 20, 2013 at http://www.tandfonline.com/doi/pdf/10.1207/s15327604jaws0702_2 .

Boal, J. 2006. Vie Et Milieu. Social Recognition: A Top Down View of Cephalopod Behavior , 56: 69-79. Accessed April 23, 2013 at http://millersville.edu/academics/scma/biology/faculty/boal-pdf/5.boal_vie_milieu_2006.pdf .

Boal, J., A. Dunham, K. Williams, R. Hanlon. 2000. Experimental Evidence for Spatial Learning in Octopuses. Journal of Comparative Psychology , Vol. 114/No. 3,: 246-252. Accessed February 15, 2013 at http://psycnet.apa.org/journals/com/114/3/246.pdf .

Forsythe, J., R. Hanlon, R. Bullis, E. Noga. 1991. Octopus bimaculoides (Pickford & McConnaughey,. Journal of Fish Diseases , 14: 431-442. Accessed February 16, 2013 at http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2761.1991.tb00595.x/pdf .

Foster, , Smith. 2013. "Two-Spot Octopus" (On-line). Pet Education. Accessed May 13, 2013 at http://www.peteducation.com/article.cfm?c=0&aid=2112 .

Kier, W., A. Smith. 2002. The Structure and Adhesive Mechanism of Octopus Suckers. Integr. Comp. Biol , 42: 1146–1153. Accessed February 20, 2013 at http://icb.oxfordjournals.org/content/42/6/1146.full.pdf+html .

L. D. Roberts, P. 2009. "Two-Spotted Octopus" (On-line). Accessed March 13, 2013 at http://jaffeweb.ucsd.edu/node/twospottedoctopus .

Marsh, J., M. Fox. 2007. Seafood Watch. Seafood Report , 1: 24-35. Accessed May 13, 2013 at http://www.montereybayaquarium.org/cr/cr_seafoodwatch/content/media/MBA_SeafoodWatch_GulfofCalifornia_Guide.pdf .

Semmens, J., G. Pecl, R. Villanueva, D. Jouffre, I. Sobrino, J. Wood, P. Rigby. 2004. Understanding octopus growth: patterns, variability and physiology.. Review: Marine and Freshwater Research , 55: 367-377. Accessed April 23, 2013 at http://digital.csic.es/bitstream/10261/30661/1/Semmens%20et%20al%202004.pdf .

Sinn, D., J. Mather, R. Anderson. 2001. Early Temperamental Traits in an Octopus ( Octopus bimaculoides ). Journal of Comparative Psychology , Vol. 115/No. 4: 351-364. Accessed February 15, 2013 at http://psycnet.apa.org/journals/com/115/4/351.pdf .

Stoskopf, M., B. Oppenheim. 1996. Anatomic Features of Octopus bimaculoies and Octopus digueti . Journal of Zoo and Wildlife Medicine , 27: 1-18. Accessed February 20, 2013 at http://www.jstor.org/stable/pdfplus/20095538.pdf .

2003. "How Does An Octopus Reproduce?" (On-line). Accessed May 13, 2013 at http://wildwetcoast.wordpress.com/2012/03/10/how-does-an-octopus-reproduce/ .

2013. "Listings and Occurences for Endangered Species in California" (On-line). Accessed March 11, 2013 at http://www.fws.gov/endangered/ .

2013. "Two-Spotted Octopus" (On-line). PBS Online. Accessed May 13, 2013 at http://www.pbs.org/oceanrealm/seadwellers/survivaldwellers/octopus.html .