The hooked squid, family Onychoteuthidae, currently comprise approximately 20–25 species (several known from only single life stages and thus unconfirmed), in six or seven genera. They range in mature mantle length from 7 cm to a suggested length of 2 m for the largest member, Onykia robusta. The family is characterised by the presence of hooks only on the tentacular clubs, a simple, straight, funnel–mantle locking apparatus, and a 'step' inside the jaw angle of the lower beak.