Paul Williams / Bearded pig (Sus barbatus) digging in sand, foraging for crabs on beach, Bako National Park, Sarawak, Borneo

Paul Williams / Bearded pig (Sus barbatus) digging in sand, foraging for crabs on beach, Bako National Park, Sarawak, Borneo

Paul Williams / Bearded pig (Sus barbatus) digging in sand, foraging for crabs on beach, Bako National Park, Sarawak, Borneo

Paul Williams / Bearded pig (Sus barbatus) digging in sand, foraging for crabs on beach, Bako National Park, Sarawak, Borneo

Juergen Freund / Timelapse of Sand bubbler crabs (Dotillidae) feeding, filtering detritus and plankton from sand and discarding the processed sand as pellets, which cover the beach, Wet Tropics World Heritage Area, Ca...

Lynn M. Stone / White Ibis (Eudocimus albus) hunting for Mole crabs (Emerita sp) along shore of Gulf of Mexico. Tierra Verde, Pinellas County, Florida, USA.

David Fleetham / Pebble crab (Leucosia pubescens) can bury itself completely in the sand to escape predators, Komodo, Indonesia.

Lynn M. Stone / Dunes and vegetative cover along Tampa Bay with tracks of Yellow-crowned night heron (Nyctanassa violacea) a predator of Ghost Crabs (Ocypodinae) that live in dune burrows), Muillet Key, St. Petersbur...

John Cancalosi / Atlantic horseshoe crabs (Limulus polyphemus) mating pair travelling to the sea, with trail through sand, Delaware, New Jersey, USA.

Ingo Arndt / Horseshoe crab (Limulus polyphemus) buried in sand, Delaware Bay, Delaware, USA, May

Ingo Arndt / Two pairs of Horseshoe crabs (Limulus polyphemus) mating with trails in sand, Delaware Bay, Delaware, USA, May

Ingo Arndt / Horseshoe crab (Limulus polyphemus) with trail in sand, Delaware Bay, Delaware, USA, May