I got 4 hermit crabs about 5 months ago for my 10 gallon. 1 died, looked like he was torn apart. About 2 months ago I moved, left the tank with my roommate. Went home a few weeks after I'd moved out, the motor had burned up in my pump, no telling how long before that but it was still plugged in... my roommate didn't help maintain the tank at all obviously.... anyway, the 3 were still alive even though there had been no circulation at all. Took them out, left them in a pitcher with some decorations and water from the tank, moved, set up again, and there they are still crawling around picking at this and that...
So yeah, they are very hardy Vanos... heh.