Visual pigments of the american eel Anguilla rostrata

The yellow staae of the American eel. Anguilla rostrata. from fresh and brackish water have mixtures of rhodopsin. P5011 and porphyropsin. P5232 with the latter predominating. Downstream migrants of the silver stage have mixtures of two rhodopsins. P4821 and P5011: and porphyropsin. P5232 the latter in only small amounts. Silver eels, which were more sexually mature and held in seawater. have only the two rhodopsins with P4821 predominating. The results generally agree with those reported for the European eel. A. angiuilla. The biological significance and uniqueness of the change in opsin during metamorphosis is discussed.