filter feeding crab?

[canuckzilla]

I just discovered a new nickle sized crab in my tank. The crab was sitting in a high current area with arms that had fans on the them. It was filter feeding with its two front arms in a rapid motion to and from its mouth. The two front arms weren't just hairy, they had specific and multiple fan like hairs/appendages.

Is every crab like this or is this a unique behavior to one species of crab?

- Gary