Ryan Photographic - Calappidae - Box or shame-faced crabs
Family Calappidae
The calappid crabs, also known as box crabs or shame-faced crabs, typically live on sandy or muddy bottoms in shallow coastal waters. The common name "box"stems from the way the crab looks when it folds in its chelipeds (pincers) tightly against the body. "Shame-faced" stems from the observation that the crab "hides its face" when in a defensive posture. There are currently 92 species known in five genera.
When threatened, the box crabs typically swim away at high speed and then seek refuge by burying themselves in the sand. Some are cryptically colored and may, instead, rely on their immobility to escape detection.
The calappids are usually specialist mollusc feeders and typically only feed on dextral (right hand twisting) snails. "Here, one of the claws is enlarged and operates with a scissor-like action that facilitates peeling open the snail. " (quote from the Map of Life website.)
Calappa hepatica Long-eyed box crab
Calappa hepatica Long-eyed box crab, Magic Bay Rao, Morotai IMG_5P7A6778