Subject: Re: Jet-black praying mantis eyes

From: [email-masked] (Eric Engelhard)
Date: 25 May 1995 18:08:06 GMT

Adam Britton - [email-masked] asked about mantids changing
eye color.

The suggestion that eye color change is the result of light adaptation
is probably correct. The insect compound eye is made up of many
repeated units, called ommatidia (singular = ommatidium). You can
easily see the external cuticle surface of each ommatidium as you gaze
eye to eye. Within each unit are cellular and acellular structures that
function in focusing light on sensory cells, called rhabdomeres. These
cells convert light energy into electro-chemical impulses sent to the
occipital lobes of the brain. Pigment cells (often two sets, primary
and secondary) surround the rhabdomeres. The arrangement can be thought
of as a tall cylinder, with the lens structures at the top, the
rhabdomeres in the center, and the pigment cells on the outer surface.
Pigment cells, as the name implies, contain pigments capable of
absorbing light. These cells can shuttle the pigment to different
locations within the cell. One result is control of the  amount of
light reaching the rhabdomeres. Another result is change in eye color.
If you are interested in anatomy beyond this simple sketch, then check
out R. F. Chapman's classic text: The Insects, Structure and Function.
The third addition was printed in 1982 by Harvard Press.

Eric Engelhard, Ph.D.
Insect Pathologist/Biker/Brewer/Beekeeper

My views are my own etc...