The Cricket Auditory System
The auditory system of the common field cricket is amazing. Sound and the ability to hear is important for both male crickets and female crickets. The males must be able to hear their own chirp and the chirps of rival males, while females need directional hearing to properly respond to the male of their choice. In both males and females, the strong hearing ability allows crickets to dodge bats by fleeing in the opposite direction of the echolocation calls. It should come as no surprise that crickets have finely tuned auditory receptors that are even capable of regenerating themselves. Yet, it still seems unbelievable that such a thing would be possible for a mere insect.
A cricket’s eardrums are located on the front of its front knees and connected with tracheal tubes. The ear, by itself, cannot sense the direction of a sound source. When functioning as a whole with the intact audio system, however, directional hearing is possible and occurs by a comparison of pressure fluctuations between the left and right ear.
Researchers at the University of Bowdoin have even proven how important it is for crickets to have both ears in order to sense direction. They hooked up a special spherical treadmill and attached a cricket to it. As the cricket walks on the treadmill, they can measure its responses to different sound stimuli. For part of the experiment, they removed one ear from each of their crickets. Over time, they discovered that the crickets began growing a new ear. Dendrites had developed and reached across to communicate to the ear on the other side, thus proving the significance of double-ear communication for cricket directional hearing.
A Cricket on a Treadmill:
The special cricket treadmill maps out the coordinates of the cricket’s steps so that the students can observe the precise direction the cricket moves when different types of sounds are played.
Filed under: Cricket Biology