Compound eyes look so crazy up close? Do you know what animals have them and how they actually help those animals see the world?
I remember trying on a pair of ‘insect eye’ glasses before and being completely confused at the way the world appeared. Those glasses broke the world down into tons of tiny images that my brain just couldn’t interpret. Well, insects have evolved to the point that they see the world through compound eyes. Here is a brief explanation on how they work and what benefits they provide insects.
What Animals Have Compound Eyes?
All insects (arthropods) and crustaceans have these kind of eyes. Mammals, birds, reptiles, and amphibians do not have them.
What Are Compound Eyes?
Each compound eye is actually made up of thousands of individual, ‘tiny eyes’, called ommatidia. The actual term is ommatidia, but for this discussion lets just call them ‘tiny eyes’.
Each of those ‘tiny eyes’ contains everything that is needed for it to see, including a lens. All of those tiny eyes make a mosaic picture. This is an image made up of all the individual dots or images seen by each tiny eye.
How Do Compound Eyes Make A Picture Or Image?
Different insects have different numbers of those tiny eyes. The more tiny eyes they have the better their resolution or ability to see. It is easiest to think of their vision like being made up of tiny pixels or dots that make up a photo, like what make up the photos on newspapers or even the image on your TV. The more tiny eyes an insect has the more dots and the more clear the picture will be. Old TVs had less tiny eyes than the new high definition TVs.
The average number of tiny eyes is 3,000-9,000, but dragonflies (flying predators) have about 25,000!
What Are Benefits Of Compound Eyes?
They are very good at detecting movement and motion.
Another benefit is that they have a very wide field of vision. Since their eyes tend to pop out in a half circle from their body they are abel to see all around them. Of course, they can’t see behind their own body, but just about anywhere else. That is one of the reasons it is hard to sneak up on a fly and catch it.