Mobile targets and sensor mobility in bat biosonar

Abstract

Many species of echolocating bats pursue highly mobile prey such as flying insects. Target mobility poses a challenge when a prey executes escape maneuvers. In these cases, bats and their prey find themselves locked in evolutionary arms races. However, prey mobility also provides the bats with opportunities for solving the problem of detecting prey buried in clutter. This applies to active as well as passive biosonar. In passive biosonar, bats frequently listen to sounds that are generated involuntarily by the motion of a prey. In active biosonar, certain bat groups have evolved highly specialized biosonar systems to detect flying prey insects by virtue of unique Doppler signatures that are generated by the insect's wing beat. Since the Doppler shifts concerned are very small, this sensory feat requires a well-integrated suit of evolutionary specializations that include sonar signal design, cochlear filtering, representations all through the auditory system, and even adaptive behavioral control of the emitted frequencies. In addition to this complexity, bats with such a biosonar system also employ a peripheral mobility where the baffles for pulse emission and reception move rapidly during biosonar operation. It remains to be seen how these mobilities fit together to support the animal's sensory abilities.Many species of echolocating bats pursue highly mobile prey such as flying insects. Target mobility poses a challenge when a prey executes escape maneuvers. In these cases, bats and their prey find themselves locked in evolutionary arms races. However, prey mobility also provides the bats with opportunities for solving the problem of detecting prey buried in clutter. This applies to active as well as passive biosonar. In passive biosonar, bats frequently listen to sounds that are generated involuntarily by the motion of a prey. In active biosonar, certain bat groups have evolved highly specialized biosonar systems to detect flying prey insects by virtue of unique Doppler signatures that are generated by the insect's wing beat. Since the Doppler shifts concerned are very small, this sensory feat requires a well-integrated suit of evolutionary specializations that include sonar signal design, cochlear filtering, representations all through the auditory system, and even adaptive behavioral control of the emi...