Here’s Looking At You, Ant

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eye

The compound eye of many ants, including a Camponotus I imaged this morning on the new focus-stacking rig, has two colors of ommatidia. Most are black, but the peripheral facets are lighter. I’ve seen this for years but had no idea why this might be the case.

A quick search on Google scholar suggests an orientation function related to light polarization:

abstract

Can anyone who knows more about insect vision than me weigh in? I’m genuinely curious.

 

Camponotus sayi
Camponotus sayi, worker from Austin, Texas.

 

Update: Micheal Bok has the answer!

4 thoughts on “Here’s Looking At You, Ant”

    1. Now that I think about it, animals with good vision (dragonflies, cats, owls, octopuses) seem to be more likely to have pale areas surrounding a dark spot than animals with poorer vision (dogs, rats, spiders, mole crickets, weevils, other insects with long antennae and small eyes). It’s not a perfect correlation, of course, but I never thought about that before. I know the pseudopupil in arthropods reflects the angle of light facing the viewer, and helps form a sort of fovea . . . man, I need to read up more on light and eyes.

  1. Bok’s explanation seems reasonable, but I’m not sure that it’s transmission you’re seeing. Your photograph seems to show a sort of moat-like groove around the edge of the eye. It’s just possible that you’re seeing a reflection of the wall of the groove. To test whether it’s transmission from cuticle underlying the edge ommatidia or reflection, a very tiny bit of black paint applied to the area just outside the eye should remove the lighter color, if reflection is the cause, but not if transmission through the ommatidium is the source of the light color.

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