There are two species of squareback crabs in Sapelo saltmarshes, Sesarma reticulatum (shown below) and Armases cinereum. S. reticulatum lives throughout the vegetated marsh, and A. cinereum lives in the marsh at its upper edge, and ventures up into the maritime terrestrial zone. Characteristically-structured fecal pellets of squarebacks (both species?) have been regularly found on standing-decaying leaf blades of smooth cordgrass (Newell and Graça, unpublished), and it is suspected that squarebacks may be invertebrate sinks for marshgrass-fungal mass. At the time of this writing, the crab in this picture had been living on standing-decaying cordgrass blades as its only food for seven months. See Newell & Porter, 1999, in Weinstein & Kreeger, Concepts and Controversies in Tidal Marsh Ecology, Kluwer.