Night Vision in Animals

The Night time world is never closed for nocturnal animals. Unlike humans, many animals possess adaptations that allow them to see even when the night sky is very dark. Animals have developed amazing adaptations to their environments. Most nocturnal animals have large eyes relative to their body size. This adaptation, along with the ability to dilate their pupils far wider than humans can, maximizes the amount of light entering into the eye.

Night Vision

Night vision is the ability to see in a dark environment. Night vision is mainly due to two adaptive features.

Spectral range

Human vision is confined to a small portion of the electromagnetic spectrum called visible spectrum.

Intensity range

Sufficient intensity range is the ability to sense very small quantities of light.

Large eyes in Nocturnal Animals

Nocturnal animals have large eyes, wider pupil, large lens and increased retinal surface to collect more light. 

Physiology of Night vision

The vertebrate eyes have Photosensitive cells called Rods and Cones. Rods are elongated cells mainly confined in the periphery of the retina.

Role of Rhodopsin

The molecules of Rhodopsin in the rods undergo a change in shape as light is absorbed by them. Rhodopsin is the chemical that allows night-vision, and is extremely sensitive to light.

Role of Tapetum

Many animals have a tissue layer called the Tapetum lucidum in the back of the eye that reflects light back through the retina.

Snakes – They use their normal eyes during the daytime to see things. During the day time , a snake's vision dependents on the movement of prey.

Bees – Bees can see light between wavelengths 300 nm & 650 nm and they can see polarized light

Fish - Some fish can see the infrared wavelengths. They have only rods in the retina.