Most species of octopuses live in burrows and crevices in the ocean floor, and are solitary when not mating, though a few live in dens with others. Some octopuses stay on the ocean floor and some swim around, but they do not migrate and stay close to their homes. Almost all octopuses are predators, eating crustaceans, worms, fish, and other molluscs and cephalopods. They trap their prey with their arms, and inject them with paralyzing saliva/neurotoxin. For hard-shelled prey, they drill a hole in the shell with help from a dissolving enzyme in the toxic saliva. Octopuses have very advanced pigment cells called chromatophores that are individually innervated from the brain. The giant Pacific octopus can change color in one tenth of a second. Muscles in their skin create even better camoflauge by changing their skin's texture.