Beaches, sand bars and spits are exposed to waves and tides on moderate-high energy coasts, and rely on drift seaweed and surf-zone phytoplankton for nutrients. Polychaete worms, bivalve shellfish and a range of smaller invertebrates burrow in the shifting sediments, while larger vertebrate animals like seabirds, egg-laying turtles and scavenging foxes can also be found at various times. Storm tides and waves periodically restructure the sediments and profoundly influence the traits of the organisms living in these highly dynamic systems.