Squid Squid Squid are cephalopods in the order Teuthida with elongated bodies, large eyes, eight arms and two tentacles. Like all other cephalopods, squid have a distinct head, bilateral symmetry, and a mantle. They are mainly soft-bodied, like octopuses, but have a small internal skeleton in the form of a rod-like gladius or pen, made of chitin. Squid can change colour for camouflage and signalling. Some species are bioluminescent, using their light for counter-illumination camouflage. Squid are members of the class Cephalopoda, subclass Coleoidea. The squid orders Myopsida and Oegopsida are in the superorder Decapodiformes (from the Greek for "ten-legged"). Two
Whip-lash squid length in some species. It is from these 'whip-like' tentacles that their common name derives. Unlike most other squid, the club of the mastigoteuthid tentacle is not significantly (usually not at all) broader than the rest of the tentacle and is covered in very small suckers—in some species, invisible to the naked eye—which impart an extremely sticky property to the clubs, themselves answering for 70% or more of the tentacle's length in some species. Many species also possess photophores (bioluminescent organs) which may be located on either the skin, the surface of the eyeball, or the eyelid. These photophores have