Steenstrup, 1857
Large or medium-sized active nektonic squids. Mantle muscular, cylindrical or conical. Fin at posterior mantle end, transversely diamond- or heart-shaped. Head large. Arms long, with strong swimming keels and two rows of suckers with toothed rings. Tentacles strong, with 4 rows (8 rows at the club end in Illex) of unequal suckers, also with toothed rings, and a short fixing apparatus usually consisting of knobs and suckers. In many genera the anterior part of the funnel pit is separated from the posterior part by a crescent-like skin fold (foveola); in some genera, posterior to it, at both sides of the funnel, some skin pockets are developed. Funnel cartilage with two deep furrows crossing in the form of an inverted "T"; mantle cartilage with two strong crossed ridges. Funnel and mantle cartilages merged together in the postlarvae of two species. Buccal membrane with 7 lappets, connectives to 4th arms attached ventrally. Many species have diverse photophores on mantle, arms, eyeball and/or gut. Gladius narrow, without fan, with short conus. Larvae are very characteristic, often called rhynchoteuthis or rhynchoteuthion. They are born with both tentacles fused together and forming a narrow "trunk" (proboscis), as in a baby elephant. On the tip of this trunk a diamond-shaped snout plate stretches laterally, with 8 suckers: 3 on the each dorsal and ventral sides, of the same size, and 2 on the lateral angles, larger in some genera than others. In late larvae the proboscis begins to divide at the base, the cleft gradually moving forward, lateral angles of the snout elongating, and finally the proboscis divides fully and the tentacles separate. The lateral angles become tentacular clubs and snout suckers - rudiments of the fixing apparatus. In some genera, at the time of proboscis division the lateral angles of the proboscis tip begin to elongate, forming small lobes resembling "ears", rudiments of club ends (dactyli). The mantle in larvae is at first barrel-shaped, later cylindrical, fins are short, petaloid. Relative length of the proboscis, size relationships of lateral to other suckers, and presence/absence of gut and eyeball photophores are characters used for the identification of larvae. ML in newborn larvae is usually about 0.8-1.0 mm. Five subfamilies, 11 genera. Nine genera and 11-12 species in the South Atlantic.
Subfamily Illicinae
Subfamily Todarodinae
Subfamily Ornithoteuthinae
Subfamily Ommastrephinae