You are attending a dinner party with a world famous animal physiologist. Over dinner the conversation turns to her latest discoveries. She says that recently, she and her team have discovered a rare species of fish that has juxtamedullary nephrons. As a student of physiology yourself you remark, "My goodness, that must mean the fish is able to __________, a physiological ability never before discovered in fish." She is so impressed that she invites you become a graduate student in her lab. Congratulations!