Sunday, January 11, 2015

Insect Vision

Thomas Shahan - Eye Arrangement of a Hogna Wolf Spider
What can insects and other arthropods see through their compound eyes?

Quick answer: they can see definite, resolved images. Some compound eyes yield a single erect image and others produce multiple inverted images. Their acuity is less than we can see with our single-lens vertebrate eye. Each optical cell in a compound eye can't form a very sharp image because the focal point always lies behind the retina.

But the view through compound eyes is not necessarily the super low-resolution hexagonal pixels or the kaleidoscopic multiplication effect that we've often seen in cartoony diagrams.

Arthropod eyes have certain advantages over our vertebrate single-lens eyes. They have a wider angle of view, infinite depth of field, fewer aberrations, and extreme sensitivity to motion. Their visual system operates within a tiny package, sometimes smaller than the head of a pin.

Most arthropods have not only the more familiar compound eyes, but also other kinds of optical sensors distributed on their bodies. These sensors may be specialized for perceiving light levels, movement, polarized light, expanded color vision, dim illumination, or heat signatures.

Eye structures vary among arthropods, a group that includes insects, spiders, crustaceans, and horseshoe crabs, plus extinct trilobites.

Engineers are working on artificial vision systems that enjoy the benefits of arthropod eye systems. They have been experimenting with imaging technology that delivers a full hemispheric field of view, using sensors crammed with hundreds or even thousands of individual imaging elements.

Artificial eye by CURVACE: Curved Artificial Compound Eye
Wikipedia on compound eyes
Wikipedia arthropod eye


Eugene Arenhaus said...

James, that's a photo of a spider, not an insect. :) Spiders do not have compound eyes, they have eight camera eyes. Insects also normally have three such "simple eyes" between their two compound ones.

Not that these jumping spiders' eyes are not fascinating - they make up for the immobile lenses of their two binocular eyes with a movable retina strip, with muscles that enable the spider to scan around the image by moving the retina around the eye chamber - as if focusing of a photo camera were done by moving the film. But compound eyes, they are not. You might want to use a dragonfly photo.

Unknown said...

That is wild.

Rich said...

He's obviously having his own point(s) of view:
If only this many-eyed specimen could paint!... Just wondering'bout the outcome

krystal said...

Bio-mimicry is awesome.Thanks for sharing!

James Gurney said...

Eugene, glad to know you're reading closely—you're absolutely right. Spiders are not insects. I called the post "Insect Vision" because it's a more familiar title than "Arthropod Vision" would be, and more likely to draw people into the subject. You'll note that I explained what the larger group of arthropods includes, including sea creatures, and I also mentioned that there are many other kinds of light receptors besides compound eyes. This is one of those subjects that expands rapidly when I started looking into it, and the best I could do was provide a very basic introduction.