The class Cephalopoda contains the largest known mollusks, one of these being the giant Pacific octopus (Enteroctopus dofleini). Cephalopods have a symmetrical body (one half of the body is the same as the other half), a head, and tenatacles or arms. The octopus, like its cephalopod cousins, uses its complex muscles in its arms/tentacles and body for flexible mobility through its water environment. The arms/tentacles are also used to grab prey and for suction.