Are the two crabs in the photo the same species? My Science Olympiad kids guessed no, but they are both Sally Lightfoot crabs (Grapsus grapsus), found everywhere along the rocky shores of the Galapagos. Young crabs are black to blend in to the lava rocks and escape predation, while the larger adult crabs can sport their bright colors without fear of being eaten. Sally Lightfoots are important scavengers of rocky shore communities, found on the Pacific coasts of the Americas from northern Peru to Mexico.
John Steinback wrote during his travels in the Sea of Cortez, “These little crabs, with brilliant cloisonné carapaces, walk on their tiptoes, They have remarkable eyes and an extremely fast reaction time…they are exceedingly hard to catch. They seem to be able to run in any of four directions; but more than this, perhaps because of their rapid reaction time, they appear to read the mind of their hunter…If you walk slowly, they move slowly ahead of you in droves. If you hurry, they hurry. When you plunge at them, they seem to disappear in a puff of blue smoke—at any rate, they disappear. It is impossible to creep up on them. They are very beautiful, with clear brilliant colors, red and blues and warm browns.”