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
Colossal squid whales and sleeper sharks), while the other predators only eat juveniles or young adults. The species was first discovered in the form of two tentacles found in the stomach of a sperm whale in 1925. In 1981, a Russian trawler in the Ross Sea, off the coast of Antarctica, caught a large squid with a total length of over , which was later identified as an immature female of "M. hamiltoni". In 2003 a complete specimen of a subadult female was found near the surface with a total length of and a mantle length of . This specimen shows that