While echolocation has many benefits, it also has costs. The most pronounced is that other animals can often hear the signals emitted by bats. Those who are able to hear the sounds include other bats, potential predators, and prey. Some moths have evolved complex ears, apparently for listening to bats. When such a moth hears calls of an approaching bat, it begins evasive maneuvers.
Some insects actually emit sounds in response to bat calls.
This apparently confuses the bat although it does not directly jam the signal. However, these features are troublesome as many lineages within Microchiroptera have apparently secondarily evolved different conditions. Several other soft-tissue characteristics are found in Microchiroptera, but not Megachiroptera. As these features can not be examined in the fossil material collected to date, it is not known whether they also occured in fossils which are closely related to Microchiroptera. Thus, these characteristics can only indirectly support microchiropteran monophyly.