10) Bats avoid obstacles and nab insects on the wing by emitting ultrasonic squeaks and interpreting the echo the sound waves make after bouncing off objects in the environment. This biological sonar, called "echolocation," is also used by dolphins to navigate murky waters.
9) Never play hide-and-seek with a shark because you'll lose. Sharks have special cells in their brains that are sensitive to the electrical fields other creatures generate. This ability is so refined in some sharks that they can find fish hiding under sand by the weak electric signals their twitching muscles emit.