Subject: What is a red land crabs respiration and how does it breath under the sand

I am asking as I have to design my own creature prefectly adapted to living on 
the sand dunes and i need to have a better understanding as to what sort of 
respiration it could have. My creature is crab like therefore I wanted it to 
have a similar respiration, however since it lives on the sand dunes, i 
figured it should have lungs instead of gills, and the red land crab lives 
solely on land so if i knew some more about it it may help me...?

Re: What is a red land crabs respiration and how does it breath under the sand