European squid propulsion. The posterior border is slightly concave. The head is relatively small and has large eyes which are covered with a transparent membrane. Like almost all squid, this species has ten limbs surrounding the mouth and beak: eight are relatively short arms, and two, which form the tentacles, are long, as they are used to catch prey. The fourth left arm of males is a hectocotylus. The European squid can grow up to 30–40 cm in the mantle length, but more usually they are 15–25 cm long. The males are generally bigger than the females and exhibit more rapid rates
Giant squid by greatly stretching the two tentacles like elastic bands. Based on the examination of 130 specimens and of beaks found inside sperm whales, giant squids' mantles are not known to exceed . Including the head and arms, but excluding the tentacles, the length very rarely exceeds . Maximum total length, when measured relaxed "post mortem", is estimated at for females and for males from the posterior fins to the tip of the two long tentacles. Giant squid exhibit sexual dimorphism. Maximum weight is estimated at for females and for males. Little is known about the reproductive cycle of giant squid.