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

Andy Rouse / Sally lightfoot crab, (Grapsus grapsus), feeding on marine iguana parasites and dead skin, Galapagos

Alex Mustard / Portrait of Sally lightfoot crab (Grapsus grapsus) on a beach. San Cristobal Island, Galapagos Islands, Ecuador. Tropical East Pacific Ocean.

Tui De Roy / Dead Sally-lightfoot crab (Grapsus grapsus) washed up in surf, Puerto Egas, James Bay, Santiago Island, Galapagos, Ecuador, May.

Sergio Hanquet / Sally lightfoot crab (Percnon gibbesi). Tenerife, Canary Islands.

Sergio Hanquet / Sally lightfoot crab (Percnon gibbesi). Tenerife, Canary Islands.

Sergio Hanquet / Sally lightfoot crab (Percnon gibbesi). Tenerife, Canary Islands.

Sergio Hanquet / Sally lightfoot crab (Percnon gibbesi) group. Tenerife, Canary Islands.

Sergio Hanquet / Gulfweed crab (Planes minutus), epibiont on Loggerhead turtle (Caretta caretta). Tenerife, Canary Islands.

Andy Rouse / Sally Lightfoot Crab, (Grapsus grapsus), at sunset, Puerto Egas, Galapagos

Andy Rouse / Sally lightfoot crab, (Grapsus grapsus), at sunrise, Galapagos

Andy Rouse / Sally lightfoot crab, (Grapsus grapsus), feeding on marine iguana parasites and dead skin, Galapagos