Salmon (IMAGE) Washington University School of Medicine Caption Salmon and other freshwater fish and amphibians supercharge their ability to see red and infrared light. Scientists at Washington University School of Medicine in St. Louis have shown that this evolutionary adaptation hinges on the activity of an enzyme that converts vitamin A1 to vitamin A2, enabling the aquatic creatures to more easily navigate murky waters. Credit National Park Service Usage Restrictions Credit to National Park Service 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.