California two-spot octopus
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|California two-spot octopus|
|Octopus bimaculoides at the Santa Monica Pier Aquarium|
Pickford & McConnaughey, 1949
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, the genome was sequenced.
O. bimaculoides can be found in coastal waters from the intertidal down to at least 20 m in the eastern Pacific along mid- and southern-California and the western side of the Baja California Peninsula in Mexico.
This species of octopus is found in the intertidal and benthic zones, from the low tide to subtidal depths of about 20 m (65 ft). It prefers sandy substrate and caves of rock or debris for hiding. It tolerates a wide temperature range (at least 60-80 °F), though it prefers 65-72 °F.
Octopus bimaculoides reaches a mantle size of 7 inches (17.5 cm) with arms to 23 inches (58 cm). Not usually heavily textured, it has several common colors, such as grey with yellow splotches, and uses highly developed crypsis (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 consequently 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 gets its name from the false eye spot under each real eye. The eye spots are known as ocelli. In O. bimaculoides, the ocellus is an iridescent blue, chain-link circle set in a circle of black.
These octopuses live one to two years. The end is signaled by egg-laying in the female and senescence in both males and females.
- Pickford, G.E.; McConnaughey, B.H. (1949). "The Octopus bimaculatus problem: a study in sibling species". Bulletin of the Bingham Oceanographic Collection. 12: 1–66.
- Albertin CB, Simakov O, Mitros T, Wang ZY, Pungor JR, Edsinger-gonzales E, Brenner S, Ragsdale CW, Rokhsar DS (2015). "The octopus genome and the evolution of cephalopod neural and morphological novelties". Nature. 524: 220–224. doi:10.1038/nature14668. PMC 4795812.
- Jereb, Patrizia Roper, Clyde F. E. Norman, Mark D. Finn, Julian K. Cephalopods of the world. An annotated and illustrated catalogue of cephalopod species known to date. Volume 3. Octopods and Vampire Squids. p. 49.
- "California Two-spot Octopus - Octopus bimaculoides". Encyclopedia of Life. Retrieved 2 October 2016.
- King, Nancy. "Octopus bimaculoides Care Sheet". Retrieved 2 October 2016.
- "CephBase: California two-spot octopus". Archived from the original on 2005.
- TONMO.com: Octopus bimaculoides Care Sheet
- eol.org: Octopus bimaculoides — Pickford and McConnaughey, 1949.
- Video of Octopus bimaculoides (California two-spot octopus)