The most extreme life on Earth part three: the great deep sea farmers

In the abyss of the deep, vents provide energy for an oasis of incredible and bizarre life.

The bottom of our oceans are a black expanse of nothingness for hundreds of kilometers in each direction. Yet in the darkness of the deep sea desert, hydrothermal vents provide a spectacular oasis, as densely populated as most ecosystems on land, boasting an array of the strangest animals on the planet.

In the deep abyss, you have to deal with crushingly high pressures, low and high temperatures but most of all, an absence of energy. About a kilometre down there is no light and without photosynthesis, or basically anything else, finding an energy source is like finding a needle in a haystack.

The vents provide energy by constantly pumping superheated water (up to 400^oC, as at high pressures the boiling point of water increases), which have previously gathered minerals in the rock below.

Large animals can’t use this chemical energy directly, but incredibly they literally farm microbes which can.

Tube worms (above and below) can grow to a massive 3 meters long, and they are gross. Perhaps the weirdest thing about them isn’t the fact that they look like a garden worm on steroids, but that they don’t have an anus. Instead, they gather their excrement in a sac, which slowly fills up and poisons them until they die. More remarkable still, their farming of microbes has gone so far that they have replaced their digestive tract with their livestock. Infact, half of the body weight of a tube worm is pure microbes, constantly using the hydrogen sulphide to provide the worm with energy.

The tube worm outside its shell showing the sac which slowly fills up with its own excrement.

Pompeii worms are equally as bizarre, but farm their microbes in a more traditional sense (kind of). They harbour the livestock on their back, let them grow and then let other worms feed on them. Vent shrimps do something similar, growing microbes on their body, but instead of letting others harvest them, they wait until they shed their skin, and then eat their old carcass.

A Pompeii worm

Considering these crazy creatures have been farming for millions of years, and we only started 12,000 years ago, maybe they’ve beaten us other things? If we look further maybe they’ve got little cars and record players, and are studying humans in tiny, deep sea laboratories.