Calappa is a genus of crabs known commonly as box crabs or shame-faced crabs.The spectacled box crab Calappa philargius occurs in sandy to slightly muddy substrates, and on the sandy shores near seagrass areas. This species is usually nocturnal.
Calappa philargius eats snails, the pincers are specialised for cracking open snail shells. .
Calappa philargius is a host of the parasites Diplothylacus calappae, Loxothylacus auritus and Sacculina scutigera.