Choanoflagellate Monosiga Brevicollis (IMAGE) University of California - Berkeley Caption Choanoflagellates are aquatic microbial eukaryotes that are distinguished by an apical flagellum (green), which is used for swimming and feeding, surrounded by a collar of microvilli or tentacles (red) against which bacterial prey are trapped. The nucleus is highlighted in blue. Credit Nicole King laboratory, UC Berkeley 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.