Opisthoteuthis bruuni is a species of finned cirrate octopus found along the western coast of South America.

Even at this small, immature stage, the octopuses displayed sexual dimorphism (sex differences).

[5] Further specimens of O. bruuni have been collected from off Chile and Peru (between 5 and 33 degrees south), over a greater bathymetric range of 250 to 512 m depth.

[4] When originally described, the extensively gelatinous body and overall form led to the suggestion that O. bruuni is potentially a mid-water or pelagic species.

[6] However, later research on O. bruuni seems to suggest a benthic habit as material is routinely collected in bottom trawls.