There are around 1,000 species of bats alive in the world today. These are broken down into the megabats, which include the large fruit bats, and the microbats, which covers a range of species, both small and large, which eat insects, fruit, nectar, fish, and occasionally other bats. With the exception of one genus, none of the megabats use echolocation, while all of the microbats do.
Echolocation is the process by which the bat sends out a brief ultrasonic sound pulse and then waits to hear if there is an echo. By knowing the time of flight of the sound pulse, the bat can work out the distance to the target; either prey or an obstacle. That much is easy, and this type of technology has long been adopted by engineers to sense objects at a distance using sound, and to work out how far away they are. However, bats can do much more than this, but the extent of their abilities to sense the world around them is largely unknown, and the research often contradictory. Some experiments have shown that bats can time pulses, and hence work out the distance to objects with far greater accuracy than is currently possible, even to engineers. Other experiments have shown that bats can sense the surface structure of objects, revealing texture. What we can gain from bats is how to learn to ‘see’ using sound. This approach may not lead us down the traditional route of signal processing, but it may let us explore different ways of analysing information, in a sense, to ask the right question rather than look for the right answer. The echolocation calls of bats, and their analysis, has been shaped by evolution for the past 60 million years. We have a great deal to learn about how bats see the world, and about how to extract information from it.