Squid usually have two tentacles and eight arms that are also called legs. A giant squid's tentacles can be up to 10 meters long and the arms up to 3 meters long. The smallest squid is only 2.5 centimeters in length total.

Squid have hooks that lie on the suckers of the tentacles that are used to grab prey. Squid have the largest nervous system in the animal kingdom. They have the ability to change colors because they have translucent skin. The colors come from chromatophores, which are pigment cells that are on the outside of the skin that expand or contract to show colors.

Tentacles are specialized feeding arms. Octopi, nautiluses, and the vampire squid lack them. The basic cephalopod arm is a muscular tube covered in hair-like filaments called cirri, with suckers or hooks on the underside. They are used to crawl, swim and seize prey. Tentacles are longer than arms, can retract into the animal's body, and have paddle-shaped tips called clubs. Clubs are densely covered in suckers. Tentacles are used by squid to quickly strike at and snatch prey.