The colorful world of the coral reef is fascinating — yet much of the color only comes up when flash photography is used. Water efficiently filters the yellow, orange and red tones out of sunlight. At depths below ten meters they are no longer perceptible. So under normal conditions, most denizens of the deep appear a uniform blueish-gray. But some fish can produce their own red light. They have fluorescent cells which absorb the blue light of the fish’s surroundings and emit it as red light. A study published in Frontiers in Ecology and Evolution now gives us an insight into the ecological importance of this mechanism.
(From ScienceDaily)– Biologists at the University of Tübingen’s Institute of Evolution and Ecology headed by Professor Nico Michiels reviewed more than 600 species of fish for an ability to produce red fluorescence. A comparison of the ecology of these fish suggests three significant functions. Predators such as scorpion fish and flatfish emit fluorescent signals distributed irregularly over their bodies. “These ambush predators are difficult to see against a substrate containing many red fluorescent algae; the signals likely improve their camouflage,” the lead author, Dr. Nils Anthes, postulates.
In plankton-eating damselfish and gobies, the red fluorescence was dominant in the area around the eye. Nico Michiels says this is probably linked to feeding: “The red light can make the eyes of tiny, mostly transparent prey light up — thereby giving away their position.” This mechanism was previously completely unknown, but can be compared to the echolocation used by bats. The researchers are now focusing on it in further experiments.
Read the full article here: https://www.sciencedaily.com/releases/2016/11/161123090858.htm