Scientists once thought sunlight, like water, was crucial
to sustain life on Earth. But we now know of deep-sea
communities of organisms that use chemical energy, rather
than energy from sunlight, as the basis for their food.
Communities of bacteria that tap the energy in hydrogen
sulfide molecules, for example, cluster around deep-sea
hydrothermal vents. There, such bacteria are the primary
producers that provide key nutrients other organisms depend on.
At the vents, water seeping under the ocean floor picks
up dissolved minerals and nutrients. Undersea volcanic activity
superheats the water where new crust is being formed. After
seeping through cracks in the Earth’s crust and reaching
a temperature of almost 600 degrees Fahrenheit, the acidic
water dissolves minerals, such as hydrogen sulfide, from
surrounding rocks. Finally, according to scientists affiliated
with NSF’s Ridge 2000 project, the hot mineral-laden
water is spewed back out into the surrounding cold ocean
waters.
Researchers wanted to learn how hydrothermal-vent organisms
live deeper in the oceans than sunlight can possibly reach.
Bacteria-like organisms, called Archaea, have developed a
unique means of converting hydrogen sulfide into food by
a process called chemosynthesis, which makes them the producers
that sustain a diverse community of animals at the vents.
Each hydrothermal vent differs in the number and type of
creatures found there, but most are composed of
- Archaea, which produce sugars needed for life through
chemosynthesis, and live within tubeworms and mollusks,
in turn providing these animals with a food source
- fish, crabs, shrimp and octopi that prey on the tubeworms
and mollusks
These incredible ecosystems extend along the sea floor
only in the reaches of a vent’s hydrogen-sulfide plume
because inhabitants need concentrated chemicals to thrive.
Even more unbelievably, NSF-supported scientists have discovered
that much of our planet’s biodiversity may exist under
the sea floor, as microbes that live in the spaces between
grains of sediment.
To learn more:
www.ridge2000.org
www.iodp.org
How do long-term
changes affect Earth's ecosystems? [Next]
|
