The octopus is a master of disguise, blending in with its environment at startling speed. These cephalopods—marine mollusks characterized by bilateral body symmetry and limbs attached to their heads—have plenty of predators to be wary of, including sting rays, sharks and other large fish. When pressured to hide, the octopus uses thousands of color-changing cells near the surface of its skin called chromatophores. At the center of each chromatophore is an elastic sac filled with either yellow, black, brown, or red pigment. The octopus expands or contracts these cells to camouflage with its background. Check out this incredible ability in the GIFs below!