I'd say they are pretty resilient.

So long as you have at least 2 crabs, deep enough substrate so they can molt (the bigger the crab, the deeper the substrate), and fresh and salt water.

They prefer temps between 70 and 80 degrees F and humidity between 60% and 80%. But my temps have dropped to around 60 (in the winter) and humidity as low as 50% and my crew are fine. They will most likely dig down and hibernate if temps are kept that low for awhile.