Grey reef sharks in Seychelles (IMAGE) Save Our Seas Foundation Caption Believed to be predators in perpetual motion, grey reef sharks had previously only been observed in motion, leading most to believe they needed to swim in order to breath. Credit Photo © Christopher Leon Usage Restrictions The image is to be used only with the accompanying press release. 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.