A cuttlefish is a marine cephalopod belonging to the order Sepiida, characterized by a soft body, eight arms, and two long tentacles. These animals are known for their ability to change color and texture, which they use for communication and camouflage. Cuttlefish have a unique internal shell called the cuttlebone, which helps with buoyancy. They are found in oceans around the world and are often studied for their advanced nervous systems and complex behaviors.