Extraction of hermit crabs from their shells by white-faced capuchin monkeys (Cebus capucinus)

Abstract

We observed two capuchin monkeys (Cebus capucinus) feeding on hermit crabs (Coenobita compressus) on the coast, and the tactics they used to extract this well-protected prey. The observations took place during the dry season at Playa Escondida beach, Puntarenas, Costa Rica. The capuchins descended from trees at the back edge of the beach to capture passing hermit crabs. Both capuchins extracted the hermit crabs from their protective shells by holding the shell with one hand and pulling the crab out with the other. Even though this was accomplished within seconds, the extraction of hermit crabs from their shells did not appear to be a straightforward task. Once the capuchins succeeded in pulling the crabs out of their shells, they consumed the soft abdomen and discarded the rest of the crab's body. To our knowledge, the consumption of hermit crabs has not been previously reported for any capuchin monkey (Cebus or Sapajus). Our observations provide a new example of extractive foraging by capuchins, and thus an additional natural context for which fine motor skills (which are highly developed in capuchins) are necessary.