How some vertebrates evolved biological sonar
The aggressor swoops low over the treetops, piercing the night with a barrage of sonar pulses and searching for telltale data bouncing back. Some prospective targets perceive the ultrasound, take evasive action, and escape. Others, the unwary ones, are fair game. When the prowling aerialist senses the faint echoes bouncing off one of these prey, he turns toward the target, quickens his chirp rate, and homes in for the kill.