34 THE CLICKING ROBOT

CHAPTER 34 THE CLICKING ROBOT Dolphins, porpoises, and certain types of whales use echolocation to navigate the ocean. They create bursts of sound, and by listening for the echo, they're able to locate distant objects. It's the perfect way to see in the dark, and Roz wanted to give it a try. Using her voice, the robot let out a powerful clickety clickety click! Then she waited for the sounds to bounce off something, anything, and echo back to her. She waited and waited, but there was no echo. Was she doing it wrong? While the robot swam through the deep, she let out bursts of clicks and hoped that eventually she'd hear them echoing back to her. And eventually, she did. It was quiet, barely a whisper, but Roz definitely heard her own echo. It seemed to be coming from her left, so she headed in that direction and let out another round of clicks. This time, the echo was a little stronger, and she knew she was getting closer. Roz continued clicking, and the echoes returned more quickly and loudly each time, until she came across a huge jellyfish. The robot

had tracked down the only other creature in the area. Echolocation worked! "Hello, jellyfish!" said the robot. "I am very happy to meet you!" The jellyfish waved his tentacles in a way that meant… well, honestly, Roz wasn't quite sure what it meant. No matter—she was just excited to have a new way to navigate. She switched off her headlights and continued swimming north in total darkness, clicking

every few seconds and listening for echoes.