“Great fleas have little fleas upon their backs to bite ’em,
And little fleas have lesser fleas, and so ad infinitum.”
Jonathan Swift (paraphrased)
While this is not quite true, here is a picture of mites on mites on ants. This image was taken using an LT-SEM (Low Temperature Scanning Electron Microscope). It shows an ant in ventral view (belly up). The original idea was to get an image of Antennophorus mites (the large mite under the head, but also one hiding behind the third pair of legs of the ant). Antennophorus are kleptoparasites, they steal food from the ants. Ants feed other ants by regurgitating small amounts of food, which are eaten by the receiving ant. That is one way ants in the nest get to eat even if they do not forage outside themselves. Antennophorus takes advantage of this. They mimic the antennal palpitation of ants begging food from their sisters using their own elongate legs, stealing the regurgitated food. Ants do not seem to be able to recognize the thieves. Only adult mites steal food, we are not quite sure what the immature mites do.
When taking this picture we realized that we saw an entire community. Not just an ant and Antennophorus, but also acarid (e.g. on the antenna) and histiostomatid (e.g. on the Antennophorus) deutonymphs and even a nematode (riding on one of the deutonymphs on the abdomen). Deutonymphs are dimorphic, second nymphal instars specialized for phoresy, that is transport on a host to a new habitat. Not quite “ad infinitum“, as in the story, but still kind of neat. Jonathan Swift might have been impressed.
About the Author: Dr. Hans Klompen is professor in the department of Evolution, Ecology and Organismal Biology and director of The Ohio State University Acarology Collection.