Hermit crab

I have recently added a hermit crab to my established tank and it has eaten 2 of my turbo snails! Orginally I was told that the crab would recieve enough food from the left over fish food that fell to the bottom. I don't think it's getting enough food. I'm looking for some suggestions as to the best way to feed the crab and what food is best to feed it. :help:

I'm not sure of the type of crab! It has red coulouring on the pincer and legs, I'll try and get a photo. It doesn't take the shell of the snail, just eats it.