It's hot, and acidic, and there's big black plumes of chimneys coming out

of the bottom of the ocean, that can be up to 50 meters tall.

They're essentially underwater volcanoes.

They can be beautiful and sparkly, or they can just look like melting old styrofoam.

They're usually covered with these amazing, huge, beautiful animals

that are just... nothing like you've ever seen before.

In the deep sea, photosynthesis is impossible.

Instead, this alien food chain is built off of chemosynthesis, where microbes metabolize

harsh chemicals, and in turn are fed on, or used by, larger animals.

Because there is no sunlight, everything is reliant on the chemicals

coming out of the bottom of the ocean, and chemosynthetic bacteria.

Either the animals all graze the bacteria or they live symbiotically with the bacteria.

The bacteria break down the chemicals and then feed the animals.

The model is probably similar to the origins of life.

It is nearly impossible to locate and investigate hydrothermal vents,

because they occur so deep in the ocean, and emit an acidic soup of chemicals

that would be toxic to a diver.

So instead, Shannon and her team at Monterey Bay Aquarium Research Institute

first send an Autonomous Underwater Vehicle, called an AUV.

It really does look like what James Bond had as a torpedo, but it's just a really cool

piece of scientific equipment that does all the hard work for us.

We send the fleet of AUVs out to map the bottom first, and then that gives us

a really good, high-resolution picture of the bottom of the ocean.

Then, it's time to use the ROVs, or Remotely Operated Vehicles, to collect data on water chemistry,

temperature, and to bring back specimens.

When you collect the animals, they're changing chemistry, temperature, light, everything.

Their proteins are pretty much unfolding, and they're pretty unhappy by the time we see them.

We have what we call Bio Box: basically a closing box so that when you collect the animals,

you can put them in kind of their environment and bring them back to the surface.

Once the specimens make it back to the lab, Shannon uses advanced techniques to sequence

their genomes and identify them, which is not always possible with the naked eye.

There's a lot of "cryptic speciation" in the deep sea:

things will look very similar, and they'll be wildly different species,

or things can look very different, and it turns out it's just a different life stage.

When Shannon and her team have identified the animals, which often turn out to be

species brand new to science, they compare the different vent sites

to determine whether these organisms are traveling between vents,

or stay isolated in one place.

A hydrothermal vent is a really great place to study population genetics because

it's essentially a giant island of food in the ocean; the next island of food

could be hundreds of kilometers away.

And so we try to use the genetics of animals to understand how those two islands are connected.

Understanding how these different sites are connected helps paint a broad picture of evolution in action.

When vents were first discovered, we thought that these were the living relics, the living fossils

that started life on Earth, because of chemosynthesis.

Using genetics, we now know that most of the animals are relatively young,

much younger than the shallow water species.

The theory is still right; the model is probably similar to the origins of life.

In fact, NASA has a really cool program to look at life on other planets,

and how chemosynthesis could help that evolve.

Recently, astronomers have been intrigued by Saturn's harsh and icy moon, Enceladus,

and hypothesized, aided by NASA's Cassini, that it may actually be home

to hydrothermal vents of its own.

After recent experiments in Austria and Germany, scientists now believe that the life from

these hydrothermal vents on Earth could actually survive and thrive on Enceladus.

But understanding how these mysterious ecosystems work is a race against time.

Hydrothermal vents are sensitive to deep-sea mining, and often are in international waters,

making them difficult to protect.

They're also sensitive to oxygen levels.

The deep sea is probably more sensitive to the extinctions that killed off the dinosaurs, for example,

because the oxygen levels dropped throughout the world and throughout the world ocean.

When we first started working on this, we thought, "Oh, these things are going to be

the poster child for what animals can evolve to and survive in climate change."

But it turns out the minute the oxygen levels dip just a little bit, everything dies.

Despite their hardcore reputation, extremophiles may not be as resilient as we thought—

something to keep in mind as we continue to explore other planets… and our own.

We're very, very privileged to be able to visit these environments.

We've only scratched the surface of exploring these vents.

More often than not, we'll find new species, new discoveries, new vent sites that are amazing,

and nothing we could've planned for.

For more episodes of Science in the Extremes, check out this one right here.

Don't forget to subscribe, and come back to Seeker for more episodes.

Thanks for watching!