Red Sea mimic blenny (Ecsenius gravieri). This harmless blenny mimics the blackfin blenny (Meiacanthus nigrolineatus), which is poisonous. By copying the shape and colouration of the poisonous blenny, which predators have learnt to avoid, the mimic blenny gains the same protective benefits. Both blennies inhabit the western Indian Ocean, and reach around eight centimetres in length. Photographed in the Egyptian Red Sea.