Marine plankton (IMAGE) University of Oldenburg Caption Typical zooplankton found in the North Sea include copepods (top right), bristle worms (polychaetes, bottom right) and hydrome-dusae (left), a class of cnidaria. Many of the tiny organisms floating in the water are barely a millimetre long. Credit Silke Laakmann, HIFMB Usage Restrictions Only to be used in connection with article and with appropriate 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.