Coral Guard-Crab (IMAGE) Smithsonian Caption When scientists removed the largest species of the guard-crabs, Trapezia flavopunctata, from the path of an army of predator sea stars, the effects were dramatic; corals without guard-crabs, or with other species of guard-crab, were eaten -- usually overnight. In Sept. 2014, Smithsonian scientists Seabird McKeon and Jenna Moore published new research highlighting the role of diversity in the healthy functioning of coral reef ecosystems, showing that guard-crab species and size classes offer different kinds of effective protection against various threats to coral reefs. Credit Courtesy of Seabird McKeon Usage Restrictions Please include the photo credit when using this photo. 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.