The beach on Heron Island is comprised largely of calcareous skeletal debris from reef organisms.The prevailing southeast winds carry finer sand upwards to form low marginal dunes. In many places around the island the beach merges with the inner sandy zone of the reef flat.  Although the beach is largely inhabited by terrestrial invertebrates, there are a number of crustaceans - ghost crabs, hermit crabs, isopods and amphipods - that spend part of their life cycle in the marine environment (often as embryos and larvae) or live in the intertidal or supratidal areas.  The intertidal region is also inhabited by a range of small bivalves, gastropods and polychaetes, and even smaller meiofaunal taxa.