The tropical mantis shrimp is known for one thing above all else: its amazing eyes. Unlike our own primitive eyes, which detect three primary colors, the mantis shrimp's can see 12. They can also perceive different forms of polarized light--light waves oscillating in a single direction. This ability is primarily thought to help the shrimp nab the transparent animals that it feasts on.
On the dimly lit seafloor, where the shrimp dig their burrows, their complex eyes have another crucial function: interspecies communication. Pigments in the shrimp's appendages absorb the ocean's ambient blue light and emit it in a yellow-green color, resulting in the characteristic spotty markings. The light's wavelength is so specific that only other members of the species can trace it, which allows the mantis shrimp both to flaunt its goods to prospective mates and to threaten encroachers.