From the United Press International, April 1, 2008
Australian scientists have discovered crayfish, known in Australia as yabbies, are able to recognize the faces of enemy crayfish.
In the study, after a fight a loser yabby was isolated and given a choice between its opponent and another crayfish not involved in the fight. The loser yabby moved towards the opponent it knew as opposed to the rival it did not, revealing it is capable of visual identity not just an acute sense of smell.
Entire article here.