This is the coconut crab (Birgus latro), a land-dwelling 

hermit 

crab that can crack open coconuts with its claws. The 

largest 

arthropod on land is found on islands across the Indian and 

Pacific Oceans and can grow to 1m from leg to leg. 

Although 

it starts out as a juvenile wearing other gastropod shells for 

protection, as an adult it grows its own tough exoskeleton.