Ummm.. yeah,

Question
Well, we went to the beach, and me and my sister REALLY wanted to buy something, different. My dad let us buy hermit crabs! He drove us to the sea shell shop, and we each picked out 2. A could days after, my big one fell out of his shell, so i thought, you know he is fine, just maybe molting or finding a new shell he is fine. Well, it was a couple days when he was just walking out of his shell, so i put him in isolation. Then, i knew he was dead, cause, he smelt the rotten fishy smell. Yes, i did cry. And yes i was devastated. Well, now my little sisters crab, is loosing limbs, more then 1. and he fell out of his shell, and looks like he is dead. But he doesn't smell? He didn't dig under sand or anything? he is just sitting there, not doing anything. Not drinking or eating. My question for you it, do you know like what's wrong? My mom read about hermit crabs and read, we were definitely doing things wrong, we had then in a small cage, plastic. with no climbing toys or saltwater(is that a need?) we were also using well water? is that bad? And, we used play sand? Just today, we bought a 10 gallon tank and filled it with play sand, and coconut dirt. more coconut dirt then sand, and we bought petrified wood, we are using saltwater, and we put the hermit crab that's out of his shell, under a piece of wood so that its not being crushed, but so that if it is alive, its comfortable, I need your help, please. The current temperature is 78 in there tank. we don't have a light bulb or a heat source. They drink normally, and barely eat. We do spray them, but only half a squirt. We do NOT spray the (maybe dead) one. Anything we are doing wrong? or that we need? And do you know what's wrong with him? And what should we do? Please help.

Answer
It is hard to say but probably something to do with the conditions. Are you dechlorinating the water? They need dechlorinated fresh and also ocean style salt water. They are sensitive to any sort of chemical in the air. A new crab sometimes will drop limbs even from being bathed, sprayed, or handled too much.

Are the water dishes deep enough to get into them up to their shell opening?