John Shaw / Sally lightfoot crabs (Grapsus grapsus) on the beach at Puerto Egas, Santiago Island, Galapagos, May.

Roberto Rinaldi / Elbow crab (Harrovia elegans) on a crinoid feather star (Crinoidea), Sulawesi, Indonesia.

David Fleetham / Horrid elbow crab (Daldorfia horrida) Raja Ampat, Indonesia.

Francisco Marquez / Triangle elbow crab (Parthenope triangula) on white background, Islas Marias Archipelago, Marias Biosphere Reserve, Mexico.