One in every five species of mammal is a bat. This incredibly successful group splits into two major camps. The so-called microbats include vampires, horseshoes and some 1,000 other species, all of which use sonar to navigate through the dark. They make high-pitched clicks and they use the rebounding echoes to map the world, just like a submarine.

The other group—the megabats or fruit bats—has fewer than 200 species. They tend to be bigger and, with one exception, they don’t use echolocation. They have neither the specialised body parts needed to produce the necessary clicks, nor the genetic signatures that are common to sonar users. Instead, they rely on their large eyes to see at night.

Or, at least, that’s