yep, it's a callianassid, Corallianassa sp., as Leslie suggested, or Glypturus sp. (although in Glypturus cf. acanthochirus that we recently collected in Venezuela the claws were mostly red-orange, but there are other species around ..)
Corallianassa was placed in synonymy of Neocallichirus by Sakai, but most folks working with thalassinideans do not follow his scheme ..
there is a bunch of species in the W Atlantic .. but send me this picture in a higher resolution (I need eyes + rostrum area), maybe I can tell more .. (the genus at least)
by the way, these animals are not so shy as you may think - extremely cautious - but not shy, and can even be lured out of the burrow for a shot (not for a catch though) with a piece of seagrass or alga - I was actually playing with one in Fiji, the game consisted to pull a seagrass stem .. the shrimp comes out only to a sort of invisible safety line, once it reaches this line it releases the seagrass and moves back ..
cheers
Art
