Octopus variabilis

Octopus variabilis
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Order:	Octopoda
Family:	Octopodidae
Genus:	Octopus
Species:	O. variabilis
Binomial name
Octopus variabilis Sasaki, 1929

Octopus variabilis, commonly known as the whiparm octopus, is a benthic species found in the northwest Pacific Ocean, specifically in the East China Sea and near Korea. O. variabilis inhabits areas of shallow muddy waters, particularly during breeding periods.^[1] This species is a member of the Octopodidae family, which consists of the most well-known octopus species.

This species is of economic importance to the coastal areas of China considering its role in stabilizing local fishery communities.^[2] In addition to Amphioctopus fangsiao, another key fishery resource to Korea and China, O. variabilis stands as one of the main species of cephalopod communities in East China.^[3] In many Asian countries, including South Korea, this small octopus is one of the most popular seafoods considering its low fat content along with its high proportions of polyunsaturated fatty acids.^[4] Considering their habits of filter-feeding along with inhabiting tidal flat sediments, these individuals tend to host a variety of microbiota.^[5] As a result, they have been noted to cause food-borne illnesses when consumed raw.^[6]

In 1929, Madoka Sasaki noted eighteen species of cephalopods belonging to eleven genera in seven families that occurred in Taiwan.^[7] O. variabilis has historically been confused with Octopus minor (Sasaki, 1920), a common benthic species distributed in northeast Asia, due to their morphological similarities.^[8] However, the two closely related species differ in their tolerance to environmental conditions and dispersal ability.^[8][9] Due to their similarities and taxonomic confusion, these species are often referred to interchangeably by regional fishermen and earlier scientific literature.^[10]

O. variabilis is one of the most abundant species distributed along the northwest Pacific Ocean, particularly in China, Korea, and Japan.^[11] Exhibiting limited dispersal potential, except for occasional movements between upper and lower tidal zones, O. variabilis adults are largely sessile, often times moving along seabeds.^[9] As a result of limited dispersal abilities, differentiation amongst O. variabilis populations has resulted, considering weak genetic flow.^[12] This species inhabits shallow, muddy environments, and exhibits behaviors of burrowing during breeding periods.^[13] Depth ranges of O. variabilis can range between 1-200 meters.^[14]

As with other members of class Cephalopod, O. variabilis is gonochoristic.^[15] Males exhibit mating behaviors by performing a variety of displays to attract potential mates.^[16] During copulation, a male inserts the hectocotylus into the female's mantle cavity, enabling fertilization.^[17] Following reproduction, adult males shortly die after spawning, while females die following the brooding period.^[18] Juveniles develop directly as they hatch from benthic-attached eggs with no evident planktonic larval stage.^[19]

O. variabilis is notably one of the most popular seafood choices in countries such as South Korea.^[20] Considering its high proportion of polyunsaturated fatty acids, low fat content, and high content of protein, it has been established as a staple seafood in many Asian countries.^[4] In South Korean fish markets, O. variabilis is sold to be eaten "raw," as it can be accompanied by a sauce.^[21] O. variabilis is a highly versatile seafood item that can be prepared in several ways, including grilling, braising, serving raw, or cooking in stews.^[22] However, because it often times consumed raw, the microorganisms within can potentially cause food-borne illnesses.^[23] Even though it is considerably rare, extreme cases have even lead to the development of anaphylaxis.^[24]

O. variabilis alongside other species such as AmphiOctopus fangsiao, are economically important species that dominate the northwest Pacific cephalopod communities.^[25] These species are fished primarily in East Asian Waters, particularly the Yellow and East China Seas.^[26] Since the 1990s, there has been an apparent increasing trend in cephalopod production, which has been accompanied by a change in species composition.^[27] Additionally, fluctuations in these compositions have been driven by large-scale environmental variations.^[28] Climate projections have indicated that suitable habitat for O. variabilis is likely to extend northward, which poses additional challenges for long-term management.^[29]