Top Bat (S20E14)

Bats have the amazing ability to "see" tiny objects in darkness using laser-like sound beams. Mexican free-tailed bats use echolocation to snatch insects at 10,000 feet, or to find their own infant in a crèche of 20 million screeching babies. Bat technology benefits humans too: echolocation can help blind people see with sound. And as pest-control agents bats save farmers billions of pounds each year. (BBC)