Habitats: Hydrothermal Vent - Characteristics
Hydrothermal Vent |
ALVIN, an ONR-research
submersible (a small submarine) operated by Woods Hole Oceanographic Institute, made an amazing discover in 1977. While diving nearly 8,000 feet (2,400 meters) on the East Pacific Rise near the Pacific Ocean's Galapagos Islands, the submersible and its three passengers happened upon a
hydrothermal vent, the first ever seen by humans! Completely isolated from the world of light, whole communities of
organisms (creatures) live in places where warm water flows from chimneys in the ocean floor. These vents are found in some of the deepest places in the ocean, far beyond the reach of normal submarines or divers.
Hydrothermal vents are formed where two
oceanic plates pull apart and erupting lava replaces the sea floor.
In these areas, extremely hot, mineral-rich fluid flows out from underneath the ocean floor's surface. The hot fluid flows into very cold water, usually 2 C, and cools down quickly. The cooled minerals in the fluid settle around the vent opening creating chimney-like formations. Some chimneys have been known to grow as tall as 6 kilometers!
Cold seeps are areas similar to hydrothermal vents. Though the cold seep waters are about the same temperature as the surrounding waters, they are called cold seeps in contrast to the extremely hot fluids from hydrothermal vents. The cold seeps support organisms similar to the hydrothermal vents though the exact make-up of the biological community surrounding them depends on the chemicals, such as hydrogen sulfide, methane, iron, manganese and silica, found in the cold-seep fluid.
Habitats: Hydrothermal Vent - Characteristics |
Tubeworms in the Pacific Ocean
(courtesy of NURP) |
Although hydrothermal vents are what we would consider a harsh environment, they are teeming (abundant) with life. As long as the vents remain active, which is usually one to two years, animals thrive there. In fact, more than 300 species live around the vents and are unique to this type of environment. These creatures, including tubeworms, fish, crabs, shrimp, clams, anemones and chemosynthetic bacteria, have learned to survive the complete darkness, the extremely hot vent water and the tremendous water pressure.
Mussels, worms and spider crabs in a seep community of the Gulf of Mexico.
(courtesy of NURP) |
At such depths, sunlight is unable to penetrate and allow plants to photosynthesize. Thus, they cannot be the basis of the food chain as they are for us and for every other creature with which we normally come in contact. Animals at these depths depend on bacteria that are able to convert sulfur found in the vent's fluids into energy through chemosynthesis. Larger animals then eat the chemosynthetic bacteria or eat the animals that eat the bacteria. In other vent creatures, the chemosynthetic bacteria live inside their bodies. Some organisms, such as the tubeworms, that live around the vents do not have a mouth or even a digestive tract as we do. The bacteria actually live inside their bodies and provide nutrients directly to the organisms' tissues.
Habitats: Hydrothermal Vent - Humans & the EnvironmentIf hydrothermal vents were closer to the surface, mining copper, manganese, and even gold from them could be quite profitable, but they are far too deep in the ocean for this to be profitable. Even if it were, such activities would destroy this unique habitat. Bacteria discovered around these vents has already begun helping break down dangerous hydrogen sulfide waste from industrial processes, and treatment with sulfer-eating microbes is allowing gold to be extracted from some rocks more easily. Some scientists have suggested that life actually began millions of years ago around hydrothermal vents.
These hydrothermal vent fields exist far from the normal activities of humans, in areas so difficult to get to that the vents were completely unknown until 1977. At the present time only a handful of extremely expensive exploration submarines can even reach them. Even with all of the valuable metals that can be found around these vents, it is still too expensive to make mining them worthwhile.
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