Like the other members of its genus, Stigmatoteuthis arcturi has very long arms in comparison with its mantle length.

Other features of the genus include pairing of the reproductive organs in the male, the central line of light organs on the head having three photophores, and the basal line eight photophores and three sawteeth.

The skin of larger individuals develops dermal warts underneath the epidermis.

[4] This mesopelagic squid is found in deep water in the tropical and subtropical Atlantic Ocean, between about 40°N and 30°S, particularly in the Sargasso Sea and Gulf of Mexico.

Juveniles with a mantle length less than 5 mm (0.2 in) occur at depths between 200 and 400 m (700 and 1,300 ft).