The gladius protrudes out between the posterior ends of the fins to form a tail.

[1] Taonius belone is a large pelagic and oceanic squid, referred to as mesopelagic.

In waters off Hawaii, T. belone undertakes a downward vertical migration as it matures.

The paralarvae have laterally compressed eyes at the ends of stalks and they can be found in the upper 400 m of the water column, while the larger juveniles occur at depths between 500 and 700 m (1,600 and 2,300 ft), and the subadults which have hemispherical, stalkless eyes inhabit depths below 700 m.[1] Taonius belone was originally described as the nominate subspecies of a species then known as T. borealis, i.e. T. b. borealis.

They are now thought of as sister species with T.belone in the tropical Indo-Pacific and T. borealis in the North Pacific.