Bright Colors Help Sea Slugs Stay Safe

Sea slugs live in the deep ocean. They do not have hard shells to protect their bodies. To stay safe from fish, sea slugs display very bright colors. These bright colors warn other animals that sea slugs taste bad or are dangerous.

For many years, scientists tried to understand these glowing colors. Most animals get color from pigments, which act like natural paint. However, pigments soak up light. This light loss makes animal colors look soft or dull.

Sea slugs create bright colors in a different way. Their skin contains tiny stacks of shiny crystals. When sunlight touches these crystal stacks, it reflects straight into our eyes. By changing crystal thickness and spacing, sea slugs make many bright shades.

Sea slugs also use a trick found in television screens. Their skin has thousands of tiny colorful dots close together. From far away, human eyes mix the dots into one solid color. Nature made tiny screen dots long before humans built digital televisions.

Besides changing colors, how else might soft sea animals protect themselves in the ocean?