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Selasa, 08 April 2008

Symbolophorus barnardi


The amount of light penetrating seawater depends upon many factors including the time of day, season, geographic location and the clarity of the water.

When light passes through water, it is absorbed and scattered by water molecules and particles in the water.

As water depth increases, the longer (red) wavelengths are the first to be absorbed and scattered. By about 10 m below the surface, most of the red and orange wavelengths of visible light are no longer present (view the pipefish natural light page). A source of artificial light must be used to view reds and oranges. For this reason, many divers carry a torch even during the day.

As depth increases the scattering and absorption of shorter wavelengths (yellows and greens) becomes evident. By about 150 m depth, even in the clearest water, human eyes can only see blue light.

Beyond about 800 m the human eye can detect no visible light from the surface. At these depths the only visible light is made by living organisms (more information on bioluminescence).

The eyes of some deepsea fishes are 15 to 30 times more light-sensitive than human eyes. Some deepsea fishes can detect light in depths down to 1300 m.

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