Hermit crabs don't breed in captivity. They need the ocean for breeding.
They are actually fairly hard to care for. They don't like it hot but they do need warmth, and some people like to provide both fresh and bracksih water for them in the enclosures.
They need fresh foods and hermit crab food. Favorites are fish flakes, veggies, and popcorn/peanut butter are favorites although treat foods.
They can live a LONG LONG time. 30+ years is not uncommon. The larger ones you see in pet stores (baseball size) are normally already 20 years old. All are captured in the wild.
Here are some I used to have:
<img src="http://members.rogers.com/mattl/shelbycheech.jpg">
<img src="http://members.rogers.com/mattl/crabcage.jpg">
Marisa
Marisa