A cuttlefish is a marine animal that looks like a small, alien spaceship gliding through the ocean. Despite its name, it's not actually a fish at all: it's a mollusk, related to squids, octopuses, snails, and clams. Cuttlefish have eight arms and two longer tentacles they use to catch prey, along with a soft body and large, intelligent eyes.

What makes cuttlefish extraordinary is their ability to change color and pattern in an instant. Their skin contains millions of special cells that expand and contract, allowing them to flash stripes, spots, or waves of color across their bodies. They use this ability to communicate, hunt, and hide: a cuttlefish can look like a rock one second and a rippling rainbow the next. Scientists consider them among the most intelligent invertebrates, capable of solving puzzles and learning from experience.

Inside their bodies, cuttlefish have a lightweight, chalky structure called a cuttlebone that helps them control their depth in the water. You might have seen cuttlebones in pet stores, where people buy them for birds to nibble on as a source of calcium. Cuttlefish live in oceans around the world, mostly in shallow tropical and temperate waters, hunting small fish and crustaceans with their quick tentacles.