<i>Chaoborus spp</i> (IMAGE) Université de Genève Caption During the day, the Chaoborus spp hide in the sediment where dissolved methane is transferred into their gas sacs. Using the buoyancy from the methane, they float to the lake surface at night to feed on zooplankton. At the surface, the methane in the gas sacs is dissolved back into the water. Credit ©UNIGE Usage Restrictions None 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.