thumb|Octopus bimaculoides observed at Nicholson Point in [[La Jolla, California in August, 2024.]]

thumb|Close-up of the [[Chromatophore|chromatophores on Octopus bimaculoides. ]]

The California two-spot octopus (Octopus bimaculoides), often simply called a "bimac", is an octopus species native to many parts of the Pacific Ocean including the coast of California. One can identify the species by the circular blue eyespots on each side of its head. Bimacs usually live to be about two years old. They are closely related to Verrill's two-spot octopus (Octopus bimaculatus). In 2015, O. bimaculoides became the first octopus to have a fully sequenced genome.

Description

Octopus bimaculoides reaches a mantle size of with arms to . Not usually heavily textured, it has several common colors, such as grey with yellow splotches, and uses highly developed crypsis, which is camouflage or color-changing to match the environment.

Octopuses achieve color change in part by chromatophores, iridophores, and leucophores. All are structures of the skin in increasing depth. Chromatophores are elastic pigment sacs with muscle fibers attached by which they can expand and contract. The leucophores are important because they allow for the reflection of white light, and allow the skin to reflect wavelengths of light which are prevalent in their habitat, and produce disruptive patterns. The other aspect to cephalopod camouflage is the brain, which contains nerves coated in chromatophore fibers, controlling coloration patterning.

This octopus is named for the false eye spot (ocellus) under each real eye. These ocelli are an iridescent blue, chain-link circle, set in a circle of black.

On its arms, the octopus possesses many "suckers" that it uses to taste. They have three hearts, two gills, blue blood, and a donut-shaped brain.

Distribution and habitat

O. bimaculoides are found in coastal waters, in the eastern Pacific along mid- and southern-California and the western side of the Baja California Peninsula in Mexico. They live at depths from the intertidal, down to at least .

It prefers rocky reefs or debris for hiding, and tolerates a wide temperature range , though prefers .

Ecology and behavior

Lifespan

These octopuses live around one to one and a half years in their natural habitat, but can live for up to two years in captivity. The end is signaled by egg-laying in the female and senescence in both males and females.

Diet

Since these octopuses do not live for long, they mature rapidly and can hunt for food to feed themselves right after hatching. Hatchlings feed on amphipods or mysid shrimp. As they grow, the list of what they eat grows with them. California two-spot octopuses eat anything they can find, like fish and crustaceans. They are nocturnal, and hunt at night. Their camouflage abilities give them an advantage while hunting.

Studies

Researchers collected and tagged the octopus species, O. bimaculatus, to conduct acoustic telemetry research. They measured the position of the octopuses in the environment over the course of two weeks, recording the daily movement of each octopus. The study showed that O. bimaculatus always moves from one den to another every few days, and likely to avoid predation, the octopuses varied their daytime movement patterns and the distances they travel. Octopus bimaculoides exhibits distinct temperamental traits, such as active engagement and aggression, from as early as three weeks old. Studies also show the species' cognitive flexibility, demonstrated through play-like behaviors and problem-solving abilities, highlighting its advanced intelligence and adaptability to fluctuating environments.

See also

  • Terrance the octopus

References

  • TONMO.com: Octopus bimaculoides Care Sheet
  • Video of Octopus bimaculoides (California two-spot octopus)
  • [Jarmoluk, K., & Pelled, G. (2025). Evidence of play behavior in captive California two-spot octopuses, Octopus bimaculoides. PLoS ONE, 20(7), 1–7.]
  • [Chancellor, S., Grasse, B., Sakmar, T., Scheel, D., Brown, J. S., & Santymire, R. M. (2023). Exploring the Effect of Age on the Reproductive and Stress Physiology of Octopus bimaculoides Using Dermal Hormones. Animals (Basel), 13(19), 3115.]
  • [Sinn, D. L., Perrin, N. A., Mather, J. A., & Anderson, R. C. (2001). Early temperamental traits in an octopus (Octopus bimaculoides). Journal of Comparative Psychology, 115(4), 351-364.]