American Oceans

What Is A Hydrothermal Vent

A hydrothermal vent is similar to an underwater hot spring, or geyser. Hydrothermal vents are fissures found on the seafloor, where cold water trickles down to meet hot magma, resulting in dramatically heated water.

Inactive hydrothermal vent in deep water

This hot water then moves back up and through the vent, picking up mineral particles along the way. The chemical mixture is then expelled from the vent, hardening and settling on the surrounding ocean floor.

Hydrothermal vents weren’t discovered until 1977, when scientists noticed areas of temperature spikes in the ocean. Over a short distance, cold water would become suddenly, and extremely, hot.

This led to the discovery of deep water hydrothermal vents, and the incredible ecosystems they support.

These vents are often found on divergent plate boundaries, which are areas where the Earth’s tectonic plates are moving apart. In these areas, cold water is able to trickle through the crust, and seep deeper towards the hot core.

Due to the extreme pressure, the water doesn’t boil, but does erupt upwards. When the water cools, minerals collected from the core settle, forming chimney shapes.

There are considered to be two types of hydrothermal vents: white smokers, and black smokers. Black smokers are hotter and larger, and white smokers are cooler. Both are rich in different types of minerals.

Hydrothermal vents are naturally occurring, and they support some fascinating sea life. They could, potentially, be the origins of life on Earth. However, due to their depth, exploring hydrothermal vents can be incredibly difficult.

Are Hydrothermal Vents Ecosystems?

Yes, hydrothermal vents support unique and unusual ecosystems in the ocean. The discovery of hydrothermal vents has actually greatly impacted our understanding of the requirements of life.

a hydrothermal vent on the ocean floor giving off heat

Some theorize that hydrothermal vents may be the reason behind life on Earth. Hydrothermal vents may not initially seem like they can support an ecosystem. The water is incredibly hot, there’s no sunlight, and the pressure is extreme.

Even scientists were surprised to discover that complex life can survive, and thrive, on hydrothermal vents.

The reason for this is that complex creatures and simple bacteria have formed a symbiotic relationship. Blocked off from sunlight, the bacteria uses a process known as chemosynthesis to live.

This is similar to plant life photosynthesizing, only rather than using energy from the light of the sun, the bacteria draws out chemicals from the vent fluids.

The more complex, multicellular organisms then use the bacteria for energy. Creatures such as the giant tube worm will shelter the bacteria within their organs. This support forms a symbiotic relationship.

These unusual ecosystems have broadened the understanding of how life can function in a variety of environments. 

Are Hydrothermal Vents Toxic?

Hydrothermal vents do release sulfide, so they can be considered toxic. However, that definition may give the wrong impression.

While sulfides are toxic, the presence of them in hydrothermal vents actually helps to support life. The bacteria around the vents convert these sulfides into energy, forming the basis of the food source for the ecosystem.

Without the toxic chemicals released from the vents, life wouldn’t be supported. 

Hydrothermal vents occur when cool water percolates through the crust, is heated, then expelled back into the cold sea. As the heated water travels through the crust, it collects minerals (typically sulfide minerals), along the way.

These toxic minerals are then expelled into the cold ocean, and solidify. The bacteria can then draw energy from these minerals, through a process known as chemosynthesis. The toxins allow life to exist without the presence of sunlight.

However, not everything can survive near a hydrothermal vent. For many types of creature, the sulfides remain toxic.

The delicate ecosystems that are found there have specifically evolved to thrive in that exact environment. The rest of us would find the toxic chemicals the vents spew to be very dangerous. 

Where Are Hydrothermal Vents Located?

The first hydrothermal vent wasn’t discovered until 1977, and part of the reason for that is the incredible depths at which they’re found.

Hydrothermal vents are generally found at a depth of 6500 feet or greater. Hydrothermal vents are found globally, most commonly on the boundaries of tectonic plates. 

The deepest hydrothermal vents that we’re currently aware of are those located in the Cayman Trough. These are 3.1 miles below the surface of the ocean, or over 16,000 feet.

Hydrothermal vents are typically found on mid-ocean ridges, where tectonic plates are diverging to form a new floor.

Because of this depth, it’s often difficult to locate hydrothermal vents. However, even before discovery, their presence had been theorized extensively. Scientists had noticed areas in the ocean of sudden temperature spikes.

They began to form an idea of what could be causing these spikes, despite being yet to find an active hydrothermal vent. The theories they developed still play a role in the finding of hydrothermal vents, as it isn’t always feasible to dive to them.

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