Sea urchins (IMAGE) University of Barcelona Caption Sea urchins can perceive the chemistry of their predators and react instantly by changing their movement patterns. Credit Jordi Pagès (UB-IRBio) Usage Restrictions Credit must be given to the creator. License CC BY 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.