An Isotomurus Springtail Species (IMAGE) Proceedings of the National Academy of Sciences Caption This is an Isotomurus springtail species. Alien species like these have, on average, greater resistance to heat than their indigenous counterparts. Credit PNAS 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.