Lights from the Abyss

Strange things are happening thousands of feet below the surface of our oceans. At these incredible depths, where sunlight is not able to penetrate, a mysterious glow of light has been discovered.

The strange lights , which are imperceptible to humans but detectable with scientific instruments, comes from ridge-top vents that eject volcanically heated mineral-containing water. Vents form where the earth's crustal plates are slowly spreading apart and magma seeps up from below to form mountain ranges (called mid-ocean ridges). A more thorough explanation of this process can be found in the Geology Science Circle under Plate Tectonics. These vents create a very unusual environment. Strange creatures, including large tube worms, clams, deep-sea fish, deep-sea jellyfish, crabs and several species of shrimp have made this place their home.

The environment where the lights have been discovered is extremely hostile. The pressure (from the enormous column of water) is so high that it will easily crush all but the strongest research submarines. Water that exits from the vents is extremely hot (400 C) while surrounding ocean water temperature is immensely cold (only slightly above the freezing point of water). The water discharged from the vents is toxic due to high concentrations of dissolved chemicals. Sunlight from the surface is nonexistent.

At first, scientists thought that the light was caused by thermal radiation, similar to that which occurs on the elements of an electric stove. Recent studies, however, have shown that the light is too intense to be due to thermal radiation alone. At one location the light was 19 times brighter than would be expected from thermal radiation.

Scientists have recently speculated that the light may be a result of the following:

Crystalloluminescence

Light may be emitted when the very hot mineral-containing water comes in contact with the cold sea water. The minerals that are dissolved in the very hot water crystallize and drop out of solution.

 

Triboluminescence

Light may be emitted when mineral crystals crack from the cold water and bang together in the turbulent water.

As strange as the light is, some of the implications are even stranger. It appears possible that the light may be sufficient to power photosynthesis. If this turns out to be the case, and photosynthesizing bacteria are discovered, this would be the first time that photosynthesis, without direct sunlight, would be observed. Just think for a moment - a discovery like this would indicate that organisms might thrive in equally hostile / unusual locations elsewhere in the universe.

I mentioned earlier that some species of shrimp have made the environment around hydrothermal ocean vents their home. Until recently, these shrimp were believed to be blind. It is now known that they have light sensing organs on the back of their shells. Scientists speculate that these sensitive eyes may be used to detect the light coming from the vents. This may be how they stay close to home. Strange indeed!