Can my red clawed crabs see in the dark?

[cornflakes]

I leave a little lamp in the aquarium so the bulb gives off heat and keeps the temp. cozy. They like to play/hang around it maybe cuz it's warm? But it's in the middle of the water. When I go to bed, I turn off the light and I'm just wondering if they can still see just fine in the dark? I'd hate to leave them stranded in the water in the dark if they can't see great and find their way back to land.

 

[Toad]

They'll be fine without the light.

 

[cornflakes]

ok thanks!