"I fly by sound rather than sight. I sleep upside down. I am the only mammal that truly flies. I pollinate many of the plants that feed you. What am I?"

Answer: A Bat. Bats navigate using echolocation — emitting ultrasonic pulses and detecting their echoes. They roost hanging upside down. They are the only mammals capable of true sustained flight. Bats are important pollinators for many fruit trees.