For example, sharks can see blue-green and yellow-green, but they cannot see red or orange. This is because the pigments in the shark's retinas are not sensitive to the wavelengths of light that correspond to red and orange.
Sharks also have a layer of cells behind their retinas called the tapetum lucidum. This layer reflects light back into the retinas, which helps to increase the amount of light that reaches the photoreceptor cells. This gives sharks better night vision than humans.
In addition to their color vision, sharks also have excellent motion detection. This is due to the fact that their retinas are densely packed with photoreceptor cells. This allows sharks to see even small movements in the water, which helps them to hunt for prey.
Overall, sharks have a very good sense of vision that is well-suited for their predatory lifestyle. They can see color and motion, but their color vision is not as sophisticated as that of humans.