VIDEO: <i>Cassiopea</i> Jellyfish (VIDEO) California Institute of Technology This video is under embargo. Please login to access this video. To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Caption The jellyfish Cassiopea spends most of its life resting on underwater surfaces, pulsating gently. Caltech scientists have now discovered that these jellyfish actually exhibit a surprising behavior: sleep. Credit Caltech Usage Restrictions with proper credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.