By measuring the lengths of the first and second segments of the thorax (T1 and T2), Keller et al. revealed that the workers of many ant species have an enlarged T1 or neck segment. The muscles within this segment are arranged in a way that has not been seen in other insects, and allow the worker ants to perform their amazing feats of strength. For example, some species are able to lift objects up to 90 times their own body weight. In ants the third segment of the thorax fuses with the first segment of the abdomen to form the propodeum.
Photograph: Scott Bauer, US Department of Agriculture. Illustration: Mariana Ruiz