VIDEO. Supersonic toothed ant jaw – Sciences et Avenir

In most ants, their jaws are thin sticks with which insects pick up food. But in others, odontomachs, widely distributed in hot regions of Africa, Asia, Australia and South America, the mandibles are real wolf traps that can work with lightning speed and fall on their victims. What’s more, Odontomachus seems to be able to repeat the operation several times if necessary to cut its prey into pieces!

Riddle: how does an insect make its skull and body resist such blows without twisting its jaw and breaking it into pieces? Because during this dazzling maneuver, the force acting on the ant is colossal. This is equivalent to several hundred times the weight of an animal, and the acceleration of the device reaches 100,000 g! It was this ballistic puzzle that was studied by a team led by Sheila Patek (Duke University, USA) together with American and British colleagues. They publish the results of their research in an article in the Journal of Experimental Biology.

Shrinking head, deforming skull

To uncover the ant’s secrets, the team filmed some people with a 300,000 frame per second camera. Analyzing the video, the researchers specifically found that during the phase where the insect “arms” its jaws, allowing them to open about sixty degrees, its entire head shrinks and shrinks by about 3%. It was here that they realized that if the animal’s skull was deformed, it was to conserve some of the necessary elastic energy to allow the jaws to open at an angle of about thirty degrees. The remaining thirty degrees are provided by a huge (1/7 of the animal’s weight!) abductor muscle inside the skull.

Thus, the researchers found that the toothed ant was able, by stretching the tendon connecting it to the end of the lower jaw, to deform the exoskeleton of the head, compressing it, thus creating a pair of opposing forces that cause the jaws to compress. turn and open.

Reproduced with permission from The Biologists Company. Sutton G.P., St. Pierre R., Kuo S.-Y., Summers A., Bergbreiter S., Cox S. and Patek S.N. (2022).

Over 50 meters per second

When an ant decides to close its formidable appendages, the energy stored in the tendons and head is suddenly released. Clack! The trap closes at over 50 meters per second with amazing accuracy, avoiding damage to the ant’s jaw.

The team suspects that this mechanism may be widespread in other insects, and suggests that engineers could draw inspiration from it to improve the accuracy and durability of microrobots.

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