Look around. Eyes are everywhere. People have them, dogs have them, squirrels have them, insects have them, turtles have them, spiders have them, squids have them, and on. and on. and on.

Eyes tell us a lot about the habits of animal species (whether mammal or insect, fish or bird). Look at the location of the eyes. A predator has eyes that face forward, so they can see their prey and zero in on them. Prey species, mammals which are not meat eaters, and most other species, have eyes on the sides of their heads, the better to watch for someone sneaking up on them!

But there is more to it than that. Here are a few interesting facts I found in the essay, “Eye Day” from 365 Days of Nature and Discovery by Jane Reynolds, Phil Gates and Gaden Robinson.1994.

Frogs have large eyes and acute vision, but are color blind.

Crocodiles’ and frogs’ eyes are positioned on top of the head, so that the animal can watch for prey while submerged.

Honeybees can detect ultraviolet light, beyond the range of human vision, so colors look quite different to them.

The compound eyes of invertebrates like dragonflies are composed of many facets, each with a separate lens. They are effective for detecting movement.

Vertebrate eyes work on the camera principle, with a single lens that focuses an image on a light-sensitive retina at the back of the eyeball.

The pupils of some night monkeys open fully after dark, giving them excellent night vision.

Eyelids clean the eye surface. In birds, a third eyelid sweeps across the eye for cleaning purposes.

So, there you have it. But that’s only the tip of the ice cream cone about vision and how it differs from species to species. Learn more!~