Ray Filters Compared (image) University of Washington Caption Filter tissue with rows of what look like fern leaflets are distinctive for each filter-feeding ray, for example here's Manta birostis, a giant manta ray, compared to Mubula tarapacana, the Chilean devil ray. Even when dried, the differences remain and could be a way to identify which animals are being hunted from the filters being sold in apothecary shops. Credit M Paig-Tran/U of Washington Usage Restrictions Credit required 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.