Little is known about the reproduction of the giant squid. It probably reaches puberty at the age of 3 years, males reach puberty at a smaller size than females. Females produce a large number of eggs, sometimes more than 5 kg, each 0.5-1.4 mm long and 0.3-0.7 mm wide. The female has one unpaired ovary at the posterior end of the mantle cavity and twin spiral oviducts.
In males, an unpaired posterior testis produces sperm that passes through a complex system of glands that eventually create spermatophores. During mating, spermatophores are ejected through a long (up to 90 cm) grasping penis, which extends from the mantle.
As the sperm moves to the eggs, it remains unclear, since the giant squid lacks a hectocotylus used for multiplication by many cephalopods. Perhaps it persists in spermatophore bags, which males spew out into the tentacles of females. This assumption is based on the presence of ancillary tendrils on the tentacles of some of the captured females.