Bats are impressive navigators. Like so many mini submarines equipped with sonar, they deftly navigate dark forests and caves by listening for the echoes of their own calls. But how bats can tell which echo to follow while flitting around in a sea of overlapping and competing signals pinging off the myriad surfaces in their environments has been a mysteryuntil now.
The word umwelt comes from biology, coined by ethologists studying animals in their natural habitats. It refers to the world as an organism can perceive it, based entirely on its sensory equipment. A bat's umwelt is built from echo. A dog's from scent. A tick's world is dominated by a single chemical cue that tells it when to drop from a branch onto a passing mammal.