Lamprey (IMAGE) Northwestern University Caption One of just two vertebrates without a jaw, sea lampreys that are wreaking havoc in Midwestern fisheries are simultaneously helping scientists understand the origins of two important stem cells. Credit T. Lawrence, Great Lakes Fishery Commission Usage Restrictions No restrictions. License Public Domain 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.