The Sally Lightfoot crab, sometimes called the red rock crab,(1) is a common sight on rocky beaches on the Atlantic and Pacific coastlines of the Americas, from Florida down to Brazil and Mexico down to Chile,(1,2,3,4) as well as on nearby islands such as the Galápagos (1,2,3,4,5) and along the Atlantic coast of Africa.(2,6) Adults, which have carapace widths of around 5-8 centimeters, are generally bright red, brown, or orange with various patterns, while young Sally Lightfoot crabs are darker-colored.(2,4) Sally Lightfoot crabs spend most of their time hiding away in rock crevices,(4,7) but when they come out to feed—primarily during low tide(4,5,7) and during less sunny parts of the day (3)—they move with the remarkable agility and speed that give them their common name.(2,4) While they feed, powerful waves often crash over them, but they are able to withstand these by flattening themselves against rocks and holding on tightly.(2,4) Although these crabs mainly eat red and green algae,(2,4,5) they will eat practically anything they can get,(4) including mussels, barnacles, other crabs, young sea turtles, dead fish, and the young of seabirds such as boobies.(3,4) They also clean the beach of other material such as broken eggs and bird and bat droppings.(3,4) Through their role as predators, grazers, and cleaners, and also through their role as prey for many animals including large birds, octopuses, Kemp’s Ridley sea turtles, and chain moray eels,(4) Sally Lightfoot crabs can play an important part in coastal ecosystems.(3,5)
- 1. Johnson, Markes E., Paul M. Karabinos, and Victor Mendia. “Quaternary Intertidal Deposits Intercalated with Volcanic Rocks on Isla Sombrero Chino in the Galápagos Islands (Ecuador).” Journal of Coastal Research 26.4 (2010): 762-768.
- 2. Davis, Christopher. “Marine Invertebrates of Bermuda: Sally Lightfoot Crab (Grapsus grapsus).” The Cephalopod Page. 6 Jul. 2011. http://www.thecephalopodpage.org/MarineInvertebrateZoology/Grapsusgrapsus.html
- 3. Gianuca, Dimas and Carolus Maria Vooren. “Abundance and Behavior of the Sally Lightfoot Crab (Grapsus grapsus) in the Colony of the Brown Booby (Sula leucogaster) in the São Pedro and São Paulo Archipelago.” Investigaciones Marinas 35.2 (2007): 121-125.
- 4. Shapiro, Leo. “Grapsus grapsus (Linnaeus, 1758).” EOL Species Rapid Response. 6 Jul. 2011. http://eolspecies.lifedesks.org/pages/15872
- 5. Vinueza, L. R., G. M. Branch, M. L. Branch, and R. H. Bustamante. “Top-Down Herbivory and Bottom-Up El Niño Effects on Galápagos Rocky-Shore Communities.” Ecological Monographs 76.1 (2006): 111-131.
- 6. Kensley, B. F. “The Occurrence of Grapsus grapsus tenuicruistatus (Herbst) at the Tsitsikama Coastal National Park (Decapoda, Brachyura, Grapsidae.” Koedoe 13 (1970): 127-130.
- 7. Johnson, Garland E. “An Ethological Study of the Rock Crab, Grapsus grapsus (Family Grapsidae) with Emphasis on Behavior Variations during Ontogeny and with Habitat.” American Zoologist 5.4 (1965): 632.
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