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When I introduced this topic last time, I realized that:

  1. I didn't define the terminology I was using, and
  2. I used some outdated terms.

For example, I mentioned spines on the epinotum as a characteristic of some species of Pogonomyrmex. About half of you probably asked, "What is an epinotum?" and the other half said, "It is now called the propodeum." Mea culpa.

In his work, Pogonomyrmex Harvester Ants:  A Study of the Genus in North America, Arthur Cole uses "epinotum" to label the first abdominal segment in what is now called the mesosoma (the midsection of the ant). As Roberto Keller clarifies, the area is now called the propodeum. (See also David Louis Quinn's discussion.)

Propodeum (in blue) armed with spines in an Acanthoponera minor worker (Scanning Electron Micrograph, Roberto Keller/AMNH)

To avoid further confusion, I'm going to develop a Pogonomyrmex glossary (and get myself into even deeper trouble).

Let's start with:

Psammophore - the long hairs that form a basket shape on the under side of the ant's head. Alex Wild has a fabulous post about psammophores.

I have to say although I realize there are excellent reasons for changing the names of both morphological characteristics and also species, it makes searching the older literature difficult. In these days of keywords reigning supreme, changing the keywords every few years results in loss of valuable information. Or maybe I'm just getting old ūüôā

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Question:

I keep companotus herculeanus (carpinter ants) [Camponotus herculeanus carpenter ants] i've got the queen to nest in a bit of rotton wood in a hollow next to the glass i want to be able to look at the nest so other ant keepers have told me to put red film over the glass as ants can't see red light but some say they can do you know? if not do you lnow how to test if they can.thanks . ...MARK

Thanks for the great question, Mark. Looking for the answer led to some cool information about ant vision.

The short answer is keeping ants in dark red light is still a good way to observe them under low light intensities. But there is evidence that ants may be able to see red, especially scarlet red, under certain conditions.

History
The famous bee biologist, Karl von Frisch, reported early in the 20th century that honey bees could see color. In fact, he was able to establish that the bees could see blue, yellow and green, as well as ultraviolet and polarized light (which we can't see). Honey bees did not appear to be able to see red.

Because ants and bees are closely related, everyone assumed their vision was similar.

However, the eyes of different species of ants vary in size and complexity. For example, the compound eyes of the worker ants of your species, Camponotus herculeanus, are moderate in size. Notice the three small, shiny  ocelli at the top of the head. Those are used for vision as well.

Camponotus_herculeanus_head_2
Camponotus herculeanus Photographer: April Nobile Date Uploaded: 11/30/2006 Copyright: Copyright AntWeb.org, 2000-2009. Licensing: Attribution-ShareAlike 3.0 (cc-by-sa-3.0) Creative Commons License

In contrast, the workers of Gigantiops destructor have huge eyes.

Gigantiops-destructor
Gigantiops destructor Photographer: Michael Branstetter Date Uploaded: 07/20/2009 Copyright: Copyright AntWeb.org, 2000-2009. Licensing: Attribution-ShareAlike 3.0 (cc-by-sa-3.0) Creative Commons License

Recently scientists have begun to check ants' ability to see colors, as well as learn more about how their eyes work.

In 2004, Deprickere, Fresneau and Deneubourg found that worker Lasius niger ants tending brood behaved differently in response to red light, as compared to foraging workers. Foraging workers were less likely to aggregate (clump together) when exposed to red light in contrast to darkness, whereas workers tending brood showed no differences in aggregation. These results suggested some sort of ability to detect red light.

By doing choice tests (operant conditioning) with workers of Myrmica sabuleti in 2007, Marie-Claire Cammaerts was able to find that ants were slightly sensitive to red at high light intensity (10,000 lux), but not at low light intensity (600 lux). There seemed to be differences between scarlet red (which has a shorter wavelength) and dark red. Dark red was not detected at either intensity.

The conclusion I make is that the darker the red and the lower the intensity of light, the less the chance that ants can detect it.

If you are curious to find out more, you can always do your own experiments. Figure out some measure of behavior, such how many worker ants bunch up together (aggregate), and then see how it changes under different types of light.

Good luck, and let me know what happens.

For more information on ant vision "see:"

Roberto Keller at the American Museum of Natural History has an excellent overview of ant vision at Homology Weekly: Compound Eyes.

Marie-Claire Cammaerts. 2007. Colour vision in the ant Myrmica sabuleti Meinert, 1861 (Hymenoptera: Formicidae). Myrmecological News 10: 41-50 available at myrmecologicalnews.org/cms/images/pdf/.../mn10_41-50_non-printable.pdf as a non printable .pdf file.

Stephanie Depickere, Dominique Fresneau, Jean-Louis Deneubourg, The influence of red light on the aggregation of two castes of the ant, Lasius niger, Journal of Insect Physiology, Volume 50, Issue 7, July 2004, Pages 629-635.

Robert Kretz. 1979. A behavioural analysis of colour vision in the ant Cataglyphis bicolor (Formicidae, Hymenoptera). J. Comp. Physiol. 131:  217-233.

Carlos Martinoya1, Susana Bloch, Dora F. Ventura and Niélsy M. Puglia. Spectral efficiency as measured by ERG in the ant (Atta sexdens rubropilosa). Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology
Volume 104, Number 2 / June, 1975: 205-210.

(Note: As I mentioned previously, I have been the ‚ÄúConsult-Ant‚ÄĚ on the Leaping from the Box website. I answer questions about ants and ant farms. From now on I will post the answers here, and when Karen has time she will also post the answers on her site.)

Isn't is funny how one thing can lead to another? I reviewed a children's book about animal tongues recently, which got me thinking about ant mouthparts and more particularly, ant "tongues."

First of all, do ants even have tongues? They don't have anything that looks like a vertebrate tongue, but they definitely have a structure that is analogous.

ant-glossa
This photo is by Imarsman at Fickr (see link below)

If you examine this photograph closely, you can see the pale tube-like structure under the mandibles (jaws) at the front of the head. It the "tongue" and it isn't spectacular from our point of view. The outermost part you see is called the glossa of the labium, as well as thin labial palps sticking out below.

In reality, tongue structures of an ant are fairly complex, because an ant mouth has a lot of jobs to do. Ants need to:

  • groom themselves,
  • socially groom others, including the larvae
  • assess food quality,
  • manipulate food,
  • ingest food,
  • give food to others via trophallaxis,
  • beg for food from others,

etc. With all those jobs, it's no wonder an ant mouth is a veritable Swiss army knife of utensils and parts. There are brushes made of setae; papillae for tasting; thin finger-like palps for tasting, begging and manipulating; and various grooves and filters for moving and processing food. The blade-like mandibles surrounding the mouth are for cutting, carrying, and in some species, catching prey. From what I read, we are still working out the details of how many of these tools function.

An ant keeps its tongue retracted when it is not feeding. Perhaps that's why the ant tongue remains somewhat of a mystery to us.

Have you seen an ant stick out its tongue?

Edit: You have to run over to Alex Wild's blog and see his new video of trap door ants. Now there's a mouth!

References:

Gotwald, W.H, Jr. 1969. Comparative morphological studies of the ants, with particular reference to the mouthparts (Hymenoptera:  Formicidae). Cornell University Agricultural Experiment Station. Memoir 408.

Hansen, L. D., and J. H. Klotz. (2005). Carpenter ants of the United States and Canada. Ithaca, NY: Comstock Publishing Associates. This book has an excellent chapter on ant morphology.

J√ľrgen Paul, Flavio Roces, Bert H√∂lldobler. How do ants stick out their tongues?¬† Journal of Morphology
Volume 254 Issue 1, Pages 39 - 52
Published Online: 31 Jul 2002 (pdf available available at Wiley Science)

J. Paul and F. Roces. Fluid intake rates in ants correlate with their feeding habits. Journal of Insect Physiology
Volume 49, Issue 4, April 2003, Pages 347-357

And for more gorgeous ant photos by Ian Marsman, go to

IMarsman blog

Imarsman Flickr

Regurgitating post shows another view of ant mouthparts.