The feeding ecology of the thornback ray, Raja clavata, was studied based on the analysis of the stomach contents of specimens caught in the south-eastern Black Sea, Turkey, between May 2003 and January 2004. A total of 198 thornback rays were analysed to describe food habits and investigate the effect of sex, size and season on diet. Thornback rays fed mainly on teleost fish (especially red mullet, Mullus barbatus ponticus) and mud shrimp (Upogebia pusilla). Other prey included harbour crab, whiting, shrimp larvae and others. No differences were observed between dietary composition of males and females, but significant differences were found between size classes and seasons. [ABSTRACT FROM AUTHOR]