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.

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

Nick Hawkins / Sally lightfoot crab (Grapsus grapsus), three clinging to rock. Isabela Island, Galapagos.

Nick Hawkins / Sally lightfoot crab (Grapsus grapsus) clinging to a rock. Isabela Island, Galapagos.

Jeff Vanuga / Sally lightfoot crab (Grapsus grapsus) feeding on algae, Mosquera Beach, Mosquera island, Galapagos Islands, Ecuador.

Tui De Roy / Galapagos sea lion (Zalophus wollebaeki) feeding on tuna watched by scavengers, including, Brown pelican (Pelecanus occidentalis urinator), Great blue heron (Ardea herodias), and Sally lightfoot crab...

Tui De Roy / Galapagos sea lion (Zalophus wollebaeki) feeding on tuna, with Sally lightfoot crab (Grapsus grapsus) and a juvenile Galapagos Brown pelican (Pelicanus occidentalis urinator) . A group of the sea lion...