Cyclothone sp.
E.Widder/Harbor Branch Oceanographic Institution *  1999
     There are many different types of fish that bioluminesce. The fish to the left is known as a "Benttooth Bristlemouth."  It is considered to be "the most common vertebrate in the world." (6)
 Most fish (along with other bioluminescent organisms) do so with a blue color.  This colored product of the oxidation of luciferin, is advantageous for a few reasons.  The wavelength of light in the visible region responsible for the blue part of the spectra (approximately 430-490 nanometers) travels furthest in liquid water.  In conjunction with, and possibly as a result of this fact,  most marine organisms' eyes are restricted to detecting only the shorter wavelengths of the visible spectrum. (4)
     However, marine organisms are not restricted to emitting blue light.  Some, such as the black dragonfish shown at right, luminesce a very red (nearly infrared) light, which lead to advantages in defensive behavior.

Monterey Bay Aquarium Research Institute

E.Widder/Harbor Branch Oceanographic Institution *  1999
It should be noted that marine organisms can emit more than one color of light.  In addition to emitting red light, the black dragonfish can emit blue light.  Both the pictures at left and right are of the same specimen of black dragonfish.
Typically fish lose their bioluminescence when caught as they exhaust their ability.  Therefore it is often difficult to obtain pictures of an animal at its natural luminescence.  This specimen did not, resulting in the spectacular picture at the right. (6)

E.Widder/Harbor Branch Oceanographic Institution *  1999


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