Squid, like octopuses, use a muscular hydrostat system to control limb movement. In addition to the eight octopod arms, they have two elastic tentacles and lateral fins. Unlike octopuses, which hide in dens, squid hide in the open by maintaining displays and postures. Both camouflage and courtship related displays may be accompanied by a variety of different postures. Arms can bend, extend, twist or splay. Combinations lead to different postures.