Eciton Eyes (Ajay, Canberra, Australia)

Dear Ajay,

As it turns out, your question was a very interesting one. After a bit of digging, we discovered that most citations on the vestigial traits of Eciton eyes trace back to Schneirla's seminal book "Army Ants: A Study in Social Organization" (1971). The most pertinent parts of the book that deal with eyes as vestigial structures are quoted below:

"Although often spoken of as blind, all army ants are sensitive to light, and many of them have eyes. New World species nearly all have two tiny degenerate compound eyes called "lateral ocelli," equipped with single lenses (Werringloer, 1932). Even the workers and queens of Old World species, which lack eyes, have a subdermal sensitivity to light." [pp. 28-29]

"By contrast, foraging army ants utilize light only in minor ways as by withdrawing in groups from bright light in a fallen tree area or at the forest edge. Light, although forcing changes in their local movements, affects the main direction of the raid very little." [pg.75]

As you can probably see, the reference you were looking for is the only real citation in Schneirla's book on the material. The rest is assumed to be observational by Schneirla himself. Although we could not locate an electronic copy, we did manage to find a hard copy of the journal in the Field Museum library, and it looks to be heavily morphological.

Why is this so interesting? It appears that there have been no direct studies targeting the neurobiology of Eciton, indicating that the evaluation of worker and queen eyes as vestigial is based on morphology alone. Males, which need functional eyes to navigate during their mating flights, have eyes of distinctly different morphology in addition to the triad of ocelli on the top of their head, which you have probably already seen on AntWeb.

Hope this helps!


Max Winston & the AntAsk Team



I was looking for information on eye structures of Eciton and discovered a comment made on the ant blog:

"Other vestigial traits are the absence of functional eyes in army ant species (see photo of Eciton burchellii below). These ants are blind, but show remains of the eyes."

Would you happen to have a reference for this? I have only got an old german reference which I have not found a pdf for!
Werringloer, A. 1932. Die Sehorgane und Sehzentren der Dorylinen nebst Untersuchungen ├╝ber die Facettenaugen der Formiciden. Z. Wiss. Zool. 141,432-524.

Any help would be greatly appreciated.

You guys are doing a fantastic job on the ant blog - keep it going!!

best wishes,

Ajay Narendra
Bldg 46
ARC Centre of Excellence in Vision Science
Research School of Biology
The Australian National University
Canberra, Australia

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