DAMSELFLY EYE Cross-section - amazing!
Most invertebrates — crustaceans and insects — have compound eyes. A compound eye is made up of many separate units called ommatidia (singular: ommatidium) strands running from left to right above. Each strand has its own surface area, lens, and optic nerve fiber. It receives light from a small part of the animals field of view. The animal’s brain integrates these views into a single image.
An insect’s compound eyes bulge out and have a wide field of view. The lenses in compound eyes can’t change focus, so insects can’t see things that are far away. However, most things that concern an insect are up close and personal. The compound eye is very good at seeing things nearby and detecting motion, as anyone who’s tried to swat a fly knows.
Text credit: http://www.sdnhm.org/kids/eyes/basics-compound.html
Photo Credit: ©Dr. Igor Siwanowicz
(he photographs all those cool mantis/lizard shots one always sees on Tumblr as well.
Eye of a common blue damselfly (Enallagma cyathigerum), by Dr. Igor Siwanowicz. Olympus BioScapes 2010 Winners.