Copyright David Liittschwager
Coral guard-crabs across the Indo-Pacific live in and fiercely defend coral reefs against predators in exchange for shelter and nutrition that the corals secrete. In September 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. (Photo Copyright David Liittschwager)
