Questions about hermit crabs?

I recently attained two new hermit crabs. The first few days they were fine, although i did notice they did not eat at all, either fresh nor pellet/powder food. I simply attriubuted this to adjusting to their new climate, and so i wasnt worried. Iv'e had them for about two weeks, and i dont think they've eaten yet. Also, they consistantly bury themselves in the sand,which of course is something that hermit crabs do, but they stay there for days on end, and do not move. It has gotten to the point at which i dig them out myself and place them on their sponge because i fear dehydradation. I have no idea whether they drink or not, but they do go right back in the sand after a few minutes. Im worried. Help?