Use of a sound-based vibratome by leaf-cutting ants.

Leaf-cutting ants harvest fresh vegetation that they then use as food for symbiotic fungi. When cutting leaf fragments, the ants produce high-frequency vibrations with a specialized organ located on the gaster. This stridulation behavior is synchronized with movements of the mandible, generating complex vibrations of the mandibles. The high vibrational acceleration of the mandible (up to three times the gravitational force at peak acceleration at about 1000 hertz) appears to stiffen the material to be cut. An identical effect is achieved when soft material is sectioned with a vibratome. This hypothesis is supported by experiments simulating the cutting process with vibrating isolated mandibles: When tender leaves were cut, the vibration of the mandible reduced force fluctuations and thus permitted a smoother cut to be made.