Steven David Miller / Sand bubble patterns created by Sand bubbler crabs (Scopimera inflata), Cape Hillsborough National Park, Queensland, Australia. September.

Juergen Freund / Wide-angle 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 Herita...

Juergen Freund / 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, Cape Tribulatio...

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

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

Ole Jorgen Liodden / Galapagos Ghost Crab (Ocypode gaudichaudii) fighting on the beach. Galapagos

Juergen Freund / Land Hermit crab using a plastic bottle cap as its home. Kavieng, Papua New Guinea, June 2010

Edwin Giesbers / Two Long-tailed / Crab-eating macaques (Macaca fascicularis) foraging on coastline at low tide, Bako National Park, Sarawak, Borneo, Malaysia

Wild Wonders of Europe / Zankl / Ghost / Sand crab (Ocypode cursor) on beach, Dalyan Delta, Turkey, August 2009

Juan Carlos Munoz / Crab walking over beach leaving tracks in the wet sand, Floreana Island, Galapagos, January

Jean E. Roche / Land crab burrowing in sand on beach {Ocypode quadrata} Guadeloupe 2000.

Ben Osborne / Saltwater crocodile returning to sea {Crocodylus porosus} Crab Is, Queensland, Australia Cape