Critters on my Emerald Crab?

[pittchic]

We just bought an Emerald crab at our LFS. After putting it in our tank we realized there are very small "critters" crawling all over him? What are these? Will they hurt the rest of the tank?

 

[electrikat]

Pic or description would help.

 

[pittchic]

I tried taking a picture but they are so small the picture turns out blurry. Basically they are very small, almost microscopic bugs. They kind of look like fruit flies (without the wings of course) and they are a yellowish brown color. They are crawling all over his head and claws.