Mantis shrimps, or stomatopods, are marine crustaceans of the order Stomatopoda. They are thought to have the most complex eyes in the animal kingdom and have the most complex visual system ever discovered. Compared to the three types of photoreceptor cells that humans possess in their eyes, the eyes of a mantis shrimp have between 12 and 16 types of photoreceptors cells. Furthermore, some of these shrimp can tune the sensitivity of their long-wavelength colour vision to adapt to their environment.