You need a fiberglass cage with a top, a special lamp, dishes, stuff for them to climb on, bigger shells for them to grow into, guages and water bottle with sprayer and special saltwater and special food and special sand and special mulchy stuff.
|Sorry this looks cloudy ... Joel had just sprayed the inside to make it tropical-ish.|
The bulbs for the lamp break if you bump them into anything. The thing is, they get very hot and you have to take the top off the cage often to water them to keep the humidity levels up. So my kids were busting a $7 bulb like once a week until my husband said, "Let's just use 75-watt bulbs from the hardware store." He's a financial genius because those are like $1.50 for 4 bulbs and they work like a charm. Likewise, you can make your own saltwater for the little guys. Check on Freecycle.org for a free cage, also.
For basic crab care, I love this site because the writer calls the crab home a CRABITAT. Love it!