We’ve been telling you that algae are at the base of all aquatic food webs and that all aquatic life is dependant upon their ability to photosynthesize. Well, we have been holding back.

In 1977, scientists discovered communities of organisms living 7,000 feet below the surface of the ocean in total darkness. These communities were centered around deep hydrothermal vents much like the geyser, Old Faithful. Mineral-rich water spews out of the vents at temperatures of up to 750o Fahrenheit and is more acidic than vinegar. Thanks to the ambient pressure of about 3,300 pounds per square inch, the water doesn’t boil. Definitely a tough place to live.

The basis of life at hydrothermal vents is Archaea bacteria. We call them bacteria, but they are as genetically different from most other bacteria as you are from a head of lettuce. These Archaea convert hydrogen sulfide into energy via chemical reactions much like plants convert sunlight and carbon dioxide into energy. To exist in the extreme environment below the sea, you must either eat the Archaea (directly or indirectly) or use them to make food for you, like the 9 foot long tubeworms do.
Toxic gasses, temperatures of up to 750 degrees Fahrenheit, more acidic than vinegar … and teeming with life. Who needs the sun when you’ve got all of this?

Tubeworms that occupy the areas around the vents have a symbiotic relationship with the Archaea. The tubeworms rely on Archaea present inside their bodies to produce energy for them. The Archaea get exposed to high concentrations of hydrogen sulfide, thanks to the tubeworm’s filtering apparatus.

This is all done without the sun, in total darkness. No plant energy is required down there. All that’s needed is hydrogen sulfide and carbon dioxide. Oh, and a little oxygen. That comes from...well...photosynthesis. For that you need algae. I suppose we’ll have to keep the sun around for a while longer.

Tony Thorpe

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