The compound eye is the way insects
and a few other invertebrates
and the horse-shoe crab
) see the world. They appear initially to have two eyes, like vertebrates
, but in fact each eye consists of multiple facets
to give the creature a near 360° range of vision.
One wonders how the world must appear to an animal with compound eyes. Do they see the world like looking through a honeycomb, or do they see it as a continuum, after all, except in exceptional circumstances (hic!) we only see one picture, not two. Actually scientists now believe that compound eyes give a pixellated view of the world, much like a computer monitor does - the more eyes the insect has the better the resolution. Compound eyes consist of anything from a few hundred to a few thousand facets, depending on the species, each having its own lens and optical nerve and contributing one spot of light (pixel) to the image. There is a very good evolutionary reason for this system in that the flicker fusion (refresh) rate is vastly superior to, say, mammalian eyes, allowing the insect to see objects as it travels at high speeds.
Make your own compound eye
Stephanie Bailey of The University of Kentucky Entomology
Department suggests that we can get an idea of what it is like to see through the eyes of an insect by making a compound eye for ourselves, so here's the 'Blue Peter
' bit :
- 5-10 egg cartons
- LARGE mixing bowl
- paint - bright, dark or metallic color
- 1 inch diameter or smaller round mirrors
- glue gun
- medium size mixing bowl
- glue (optional)
To begin with, cut up the egg cartons into individual 'eyes.' Invert the LARGE mixing bowl, and cover with 1 or 2 layers of newspaper. Using the glue gun, attach individual eyes to each other, or to the newspaper (hole-side down) covering the bowl, using the bowl as a mold. The closer together the eyes fit, the better.
Once the inverted bowl is covered with individual eyes, rip sheets of newspaper into thin strips. In the medium size mixing bowl, mix flour and water into a paste (paper mache). Adding extra glue is optional
Use the newspaper, dipped in paper mache paste, to fill and smooth out the spaces in between individual eyes. Allow to dry. This may take one to several days
Gently pull the compound eye off of the large mixing bowl. If some of the newspaper in- between sticks, don't worry. Add a layer of paper mache newspaper strips to the inside part of the compound eye, again smoothing out and filling in spaces between the individual eyes. Allow to dry.
Once the compound eye is completely dry, gently remove from bowl. Cover both surfaces of the eye with at least 2-3 coats of spray paint, in a bright, dark, or metallic color.
On the inside (concave side) of the compound eye, CAREFULLY hot glue a mirror to the bottom of each individual eye.
By looking into the compound eye, you can get an idea of what an insect might see.