Goby fish (Amblyeleotris sp.) and shrimp (Alpheus sp.) in front of their burrow. The fish and the shrimp live together in a Symbiotic relationship where the shrimp digs and cleans up a burrow and the fish warn the almost blind shrimp against predators.

The picture has a blueish tint over it, because it was taken without a flash at 15 meters below sea level. At these depths this is what the world actually looks like; one needs a flash or torchlight to see the colors that are filtered out by the water.

Picture taken by Jan Derk in April 2004 in Koh Tao, Thailand.
http://commons.wikimedia.org/wiki/User:Janderk

From: http://en.wikipedia.org/wiki/Image:Goby_fish_with_shrimp.jpg