Hell as Habitat

Image: NOAA
Darkness spews into the darkness.

There is a Hell on Earth. A real one, not that silly fake one. It's a place where our glorious Sun is a long banished frivolity. A place of such insurmountable evil that chocolate is frozen by the cold, melted by the heat and crushed by the pressure. It's so dark that if you drop your chocolate, it will be lost and gone forever. Indeed, it's so dark that the Tree of Chocolate won't even grow.

Chocolate! Why have you forsaken us!

We're talking about hydrothermal vents.

It's all to do with the disastrous geological life of our planet. The tectonic plates dance their slow, ancient dance across the gooey honey that is the rock beneath the Earth's crust. On one side they collide into each other, causing earthquakes and volcanoes. On the other, they separate. Causing earthquakes and volcanoes.

Image: NOAA
White smoker.

Some of this happens dramatically on land, but it can also be a lot more relaxing. In fact, there are people who spend a lot of money to see the geysers and jump into the hot springs that are part of what's called "volcanic activity". This gives us a hint as to the double edged nature of our living planet.

Volcanoes are bad, but it's this geological life that provides us with the minerals and temperature moderation we depend on.

This is even more clear in the bottom of the sea, where most of the boundaries between parting tectonic plates are situated. Mid-ocean ridges form where magma comes up and cools, creating an underwater mountain range across the world and in every ocean.

But there is something else that boils and broils from the ocean floor in these grimly alive areas: water. Much of it sea water that seeped into volcanic rock, was heated and is now liberated with incredible violence.

Image: NOAA
A million crabs frolic in their luscious habitat.

This is water with a temperature of some 60 to 460 °C (140 to 860 °F), compared to to an ambient deep sea temperature of about 2 °C (35 °F).

It's kept liquid by the ridiculous pressure, which can even cause it to become a supercritical fluid. This is weird stuff that can go through solids as if it was a gas, but dissolves minerals like a liquid.

It can also have a pH as low as 2.8, about as acidic as vinegar. :X

But the main thing is those minerals. They are mostly sulphides drawn up from beneath the Earth's crust. These sulphides bring with them all sorts of other elements that may be deposited as they make contact with the cold, ocean water.

Image: NOAA
The yellow stuff is bacteria. Lots and lots of bacteria.

It's these deposits that make the black and white smokers. They're chimneys that spew forth yet more hot waters from the underworld, their colour determined by the minerals in their effluence. Some have been found to be up to 60 m (200 ft) tall and some have been seen to grow at a rate of 30 cm (1 ft) a day.

But there is one deadly poison that is of particular importance. Hydrogen sulphide is usually a stinking waste product of bacteria digesting without oxygen. It's responsible for bad smells in sewers and swamps and is toxic to most life. But in hydrothermal vents there are bacteria that get all the energy they need from it. They may be in such abundance that they form mats several inches thick.

And thus, in total ignorance of the Sun, a whole ecosystem may develop. Creatures here do more than survive, they thrive. There, in the midst of heat, poison and darkness, is a bustling community. An oasis in the desert, with a density of life tens of thousands of times greater than surrounding areas not similarly blessed with a direct link to the pits of Hell.

We'll take a look at some of those demons and devils next week.