[4] M. longimana is a large squid, the adults can grow to a mantle length of 740 mm, which is characterised by the presence of 33 hooks and marginal suckers throughout the tentacular club during subadult years.

[5] The type material of this species, consisting of three specimens caught at the surface and a depth of 50 m, was collected just north of the South Orkney Islands[6] and is deposited at the Zoological Museum of Moscow State University.

Its range may be circumpolar with an Antarctic and Sub-Antarctic distribution,[8] stretching as far north as South Georgia and the Tasman Sea.

Several prey have been identified for the diet of M. longimana, with krill as the main source of food.

However, indirect methods have pointed for other high trophic level prey as other crustaceans and lanternfish.