[1] The octopus is most commonly killed before being cut into small pieces and served, with the nerve activity in the octopus's tentacles making the pieces move posthumously on the plate while served.

[2][3][4] The octopus's highly complex nervous system, with two-thirds of its neurons localised in the nerve cords of its arms, lets the octopus show a variety of reflex actions that persist even when they have no input from the brain.

[8] Vocabularies in the two Koreas differ on nakji: South Koreans call Octopus minor, a small kind of octopus (often mistranslated as "baby octopus") nakji, while North Koreans call a squid nakji (nakchi in McCune–Reischauer romanization).

Octopuses' limbs contain neurons, where the extremities continue to move and the suction cups along its tentacles maintain their gripping power that might attach to one's throat, even after getting detached from the body and doused with sesame oil,[9] which presents a potentially fatal choking hazard.

[10][11][12][13] Sannakji is served in Korean restaurants that serve sliced raw fish, but it also can be found at bars as a snack to accompany alcoholic beverages, such as soju.