Many organisms manage fine, or better, without eyesight, but nevertheless eyes are extremely useful. Eyes have evolved on at least 40 separate occasions, in different branches of the animal family tree. On one of those occasions, around 500 million years ago, the early insect/crustacean branch gained their eyesight.
Today, please join me on a quick tour of insect eyes. Insects as a group have two types of eyes: simple and compound.
Simple eyes
Simple eyes, or ‘ocelli’, only detect light intensity, they do not form an image. Gradual changes in light helps insects tell the time – both hours and seasons. Springtails (close insect relatives) have up to six ocelli, but in modern insects, ocelli are usually found in triplets – unless of course they are absent.
Those bulging fisheye lenses must be exceptionally sensitive. One simple eye (seemingly with a faint pink filter) points forward, two simple eyes (with yellow filter) point left and right. One can only guess what sort of visual cues this flower mantis is recording as it picks the perfect perch. It also has two large, grey-green compound eyes.
Read the whole article in Leopard’s Echo, a bi-annual online magazine of Kloof Conservancy.
EASTERaction 