At Risk (image) University of Illinois at Urbana-Champaign Caption Marine iguanas, including these on Isla Fernandina, live in large aggregations on the rocky shores of the islands. Some harbor bacteria that are resistant to antibiotics commonly used in humans. Credit Roderick Mackie Usage Restrictions Photo may be used only to accompany articles about the research described in this release. Credit required: Roderick Mackie. 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.