A tool to sing louder and an amplifier to hear better

Crickets use sound to mediate one their most important social interactions, finding and selecting mates. The louder the sound they can make, the further it reaches and more attractive it is. Most crickets increase their acoustic space by tuning the structural mechanics of their morphology. In most species, song producing wings and sound recieving eardrums resonate at the same frequency, forming a simple matched filter system. Tree crickets, however, use communication strategies that can be considered more active. In this talk, I will present some research which shows how the signallers, the male tree crickets use a behavioural strategy to make themselves louder. They manufacture a baffle, a tool that makes them louder. In fact, using a series of models and experiments, we found that not only do they manufacture a tool, but they manufacture an optimal tool. On the reciever end, female tree crickets use an auditory amplifier. They have an active physiological system that selectively amplifies their auditory mechanics. Using careful neurobiology, we show that the amplifier does not make them more sensitive in comparison to other crickets. Rather, it allows them to alter the frequency they are sensitive to, in response to ambient temperature. This allows them to remain sensitive to males whose signalling frequency also changes with temperature. What is even more remarkable is that this amplification appears to be achieved through the activity of only a handful of motor proteins. Both findings underline the richness of invertebrate behaviour and biophysics, and point to a wealth of innovations yet to be discovered even among these 'simple' organisms.