Dogs' ability to see in darkness stems from the structure of their eyes. They have large pupils, which let in more light. Their retinas have a lot of light-and-motion-sensitive cells, called rods<span>. These distinguish light from shadow. And most importantly, dogs' eyes, like those of cats, some birds and fish, and nocturnal predator animals, have a mirror-like membrane called a </span>tapetum lucidum<span> at the rear of the eye. The tapetum allows light that is not absorbed by the rods to rebound to the retina, letting it take in more light, which enables the dog to see better.</span>
