Ants are one of the most successful animal groups on the planet. They can inhabit anything from temperate soil to rainforests, desert dunes, and kitchen counters. They are social insects, and their teamwork has long been considered one of the key factors leading to the success of their colonies. It is known that ants are able to lift or drag objects many times their own weight. But due to the fact that previous research has focused on the social aspects of the ant colony, the study of the individual ant has not received the necessary attention. Now researchers at the Okinawa University Institute of Science and Technology (OIST) and the Sorbonne University in Paris have figured out why ants are so powerful. The results are published by the journal Frontiers in Zoology.
Scientists took X-rays and created three-dimensional models of the insect’s ribcage – the central unit of their body – to analyze the muscles and internal skeleton. A new study hypothesizes that the loss of flying ability in a group of worker ants is directly related to the evolution of their strength abilities.
“Worker ants are descended from flying insects,” explains Professor Evan Economo, who heads the OIST Biodiversity Division. “We have always assumed that it was the loss of the ability to fly that helped them optimize their performance on the ground.”
In general, the ability to fly imposes serious restrictions on the physique. In flying insects, wing muscles occupy most of the chest – sometimes more than 50%. This means that other muscles that are used to support and move the head, legs, and abdomen are constrained and pressed against the exoskeleton.
But once these restrictions are removed, all of the space in the chest becomes open, which the researchers suggest allows the remaining muscles to expand and reorganize.
Previous research in this area has focused on the external structure of ants. However, with the technology available at the OIST, scientists have been able to get a detailed picture of what is happening inside the chest. The researchers carried out detailed analyzes of two distantly related ant species, including wingless worker ants and flying queens.
Scientists have used advanced X-ray technology to scan internal and external anatomy. Such as, for example, the computed tomography used in a hospital, but with a much higher resolution. Based on these scans, the experts mapped all the different muscles and modeled them in 3D. The result is a detailed view of the inside of the chest. They then compared the research results of the two species with a number of other ants and wingless insects.
As expected, the researchers found that the loss of the ability to fly allowed the worker ants to successfully rearrange their ribcages. “Inside the chest of a worker ant, everything is beautifully integrated into a tiny space,” explained Dr. Christian Peters, lead author of this article, who was a research professor at the Sorbonne University. “All three muscle groups have increased in size, giving the working ants more strength and power. The geometry of the neck muscles that support and move the head has also changed. Internal muscle attachment was also different.”
Interestingly, while studying wingless wasps, scientists found that these insects reacted in a completely different way to the loss of the ability to fly. Representatives of this species live alone and consume food when they find it. On the other hand, ants are part of the colony. They hunt or gather food, which must then be carried to the nest for the queen and younger relatives. It makes sense that selection pressure that promoted portability was logical.
For centuries, ants have been studied in terms of their behavior, ecology, and genetics, but, as the researchers emphasized, the reason for their strength has so far been ignored. The next step is to develop more detailed biomechanical models of the functioning of various muscle groups. In addition, scientists will undertake similar studies of the lower jaw and legs.