Steenstrup, 1875 sensu lato
Giant squids, largest of all invertebrates. Mantle narrow, cylindrical, tapering into short tail. Fins small, transverse-oval in larvae, longitudinal-oval in juveniles, semicircular or semioval, not reaching mantle end in adults. Head moderately wide. Arms very long, tentacles extremely long. Arms with 2 rows of suckers. tentacular club with a group of small suckers in many rows in carpal part and 4 rows of suckers in long central part; suckers of two central rows much larger than marginal. Fixing apparatus stretched along almost entire stem. Funnel cartilages simple, straight. Connectives from buccal membrane attached to 4th arms dorsally. Gladius with short wide rachis, acute behind, with small end conus, not reaching mantle end. No photophores. ML up to 5 m, usually to 1-2 m.
Supposedly 3 subspecies or vicariant species with circumglobal bi-subtropical or anti-equatorial distribution: Architeuthis dux dux Steenstup, 1875, in the North Atlantic; Architeuthis dux martensi (Hilgendorf, 1880) in the North Pacific; and Architeuthis dux sanctipauli (Vélain, 1877) in the Southern Hemisphere. Adults commonly caught near the bottom in the upper bathyal. An undescribed small species of this genus was recorded off Florida and Madeira.