The California two-spot octopus (''Octopus bimaculoides''), often simply called a "bimac", is an

octopus An octopus ( : octopuses or octopodes, see below for variants) is a soft-bodied, eight- limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefis ...

species native to many parts of the Pacific Ocean including the coast of

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...

. 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 ''Octopus bimaculatus'', commonly referred to as Verill's two-spot octopus, is a similar species to the ''Octopus bimaculoides'', a species it is often mistaken for. The two can be distinguished by the difference in the blue and black chain-like ...

''). In 2015, the

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ...

was sequenced.

Description

''Octopus bimaculoides'' reaches a mantle size of 17.5 cm (7 inches) with arms to 58 cm (23 inches). Not usually heavily textured, it has several common colors, such as grey with yellow splotches, and uses highly developed

crypsis In ecology, crypsis is the ability of an animal or a plant to avoid observation or detection by other animals. It may be a predation strategy or an antipredator adaptation. Methods include camouflage, nocturnality, subterranean lifestyle and ...

(camouflage or color-changing to match the environment). Octopuses achieve color change in part by

chromatophores Chromatophores are cells that produce color, of which many types are pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals and birds, in contrast, ...

iridophores Chromatophores are cells that produce color, of which many types are pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals and birds, in contra ...

, and

leucophore Chromatophores are cells that produce color, of which many types are pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals and birds, in contra ...

s; 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 A cephalopod is any member of the molluscan class Cephalopoda ( Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, ...

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.

Distribution and habitat

''O. bimaculoides'' can be found in coastal waters from the

intertidal The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species ...

down to at least 20 m (65 ft) in the eastern

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

along mid- and southern-California and the western side of the Baja California Peninsula in Mexico. This species of octopus is found in

subtidal The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth. From the point of view of marine biology it forms a relatively stable and well-illuminated ...

to a depth of 20 m (65 ft). It prefers rocky reefs or debris for hiding. It tolerates a wide temperature range 15-26 °C (60-80 °F), though it prefers 18-22 °C (65-72 °F).

Ecology and behaviour

Lifespan

These octopuses live one to two years. The end is signaled by egg-laying in the female and

senescence Senescence () or biological aging is the gradual deterioration of functional characteristics in living organisms. The word ''senescence'' can refer to either cellular senescence or to senescence of the whole organism. Organismal senescence inv ...

in both males and females.

Diet

Hatchlings feed on

amphipods Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far descri ...

mysid Mysida is an order of small, shrimp-like crustaceans in the malacostracan superorder Peracarida. Their common name opossum shrimps stems from the presence of a brood pouch or "marsupium" in females. The fact that the larvae are reared in this ...

shrimp Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...

Genetics

In recent years new technology, such as genome sequencing, has provided new information on the large amounts of clustered protocadherins (PCDH) in ''Octopus bimaculoides''. The octopus was found to have 168 PCDH genes, about 120 clustered and 50 non-clustered PCDH. Unlike what has been documented about mammalian clustered PCDH, octopus PCDH are clustered around the genome in an organized manner creating a head-to-tail arrangement.

References

External links

TONMO.com: Octopus bimaculoides Care Sheet

Video of ''Octopus bimaculoides'' (California two-spot octopus)
{{Taxonbar, from=Q2616929 Octopuses Molluscs of the Pacific Ocean Cephalopods of North America Western North American coastal fauna Fauna of California Molluscs of Oceania Molluscs described in 1949