This is a Red Mangrove Crab. It is about 150mm (6") wide. What does it eat?

Shrimps, small crustaceans and algae. Like the flamingo, the red colour of the crab's pincers come from the carotenoids in their diet of animal and plant plankton

Mangrove leaves. It lives in a hole in the mud and it can detect the vibration caused by one falling leaf. It then runs out and grabs it and takes it back underground

It does eat small crustaceans, algae and mangrove leaves, but it is primarily cannibalistic, eating young Red Mangrove Crabs; smaller or weaker, often elderly, adults