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
Squid and cross-linked proteins, which is used to kill and tear prey into manageable pieces. The beak is very robust, but does not contain minerals, unlike the teeth and jaws of many other organisms, including marine species. The stomachs of captured whales often have indigestible squid beaks inside. The mouth contains the radula, the rough tongue common to all molluscs except bivalvia, which is equipped with multiple rows of teeth. In some species, toxic saliva helps to control large prey; when subdued, the food can be torn in pieces by the beak, moved to the oesophagus by the radula, and swallowed.