Otolith (IMAGE) Purdue University Caption Purdue University researchers are analyzing structures called otoliths, pictured here, taken from fish larvae as part of a study to learn how young fish vital to Lake Michigan's ecosystem might cope with future climate change. The tiny calcium carbonate structures grow in fish larva. Because the structures grow in layers as the fish age, they possess rings similar to tree rings that can be analyzed under a microscope to gauge the age and growth characteristics of the larvae. Credit Tomas Hook, Purdue University Department of Forestry and Natural Resources Usage Restrictions None 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.