You are climbing into a titanium ball the size of a walk-in closet. It is 17 February 1977, the sea is black, and in eighty-three minutes you will see something no biology textbook on Earth has predicted.
The submersible is called Alvin. The part of it that keeps you alive is a titanium ball less than two metres across, with three small forward windows and just enough room for a pilot and two scientists to sit with their knees touching.
Beside you: Jack Corliss, a geologist from Oregon State, and Tjeerd van Andel from Stanford. At the controls, pilot Jack Donnelly. Nobody aboard the ship is a biologist. Nobody thought they would need one. You are here to look for hot water leaking out of a crack in the planet — a prediction from plate tectonics that no human had ever actually seen.
You are going down two and a half kilometres. Take the handrail. Mind your head.
Press Descend and watch the four invisible things become visible: the light going out, the water going cold, the pressure piling up, and the cups strapped to the outside getting smaller.
Every crew that dives in Alvin straps polystyrene cups to the outside. At the bottom the pressure crushes them to thimbles — perfect, shrunken, and still cup-shaped. You keep them.
Before anyone risked a human being, the team dragged ANGUS — a two-tonne steel cage of cameras and thermometers, nicknamed the "dope on a rope" — four and a half metres above the seafloor for twelve hours. It shot 3,000 photographs along sixteen kilometres of ocean bottom, in total darkness, at 2,500 metres.
Its temperature sensor could feel a change of 0.005 °C. Shortly after midnight it registered a warm spike that lasted three minutes. Then the film came up, and it had to be developed before anyone knew anything. Roll it.
Water shimmers out of a crack in the lava like heat off a road, then turns cloudy blue as minerals crystallise out of it. The probe reads 8 °C where the ocean has no business being warmer than 2. And everywhere — everywhere — there are animals.
Corliss picks up the acoustic telephone to Debra Stakes, a graduate student on the ship above, and asks her the question that changes biology: "Isn't the deep ocean supposed to be like a desert?" She says yes. He says: "Well, there's all these animals down here."
They named the first site Clambake 1. Later dives found Dandelion Patch, the Oyster Bed, and a field of red-tipped worms they called the Garden of Eden.
Every food chain you were ever taught starts with sunlight. Grass, plankton, leaves — something green catches a photon and builds sugar. Two and a half kilometres down, no photon has arrived in the entire history of the place. So what are those clams eating?
The answer came out of the water samples, and you could smell it before you could measure it: rotten eggs. Hydrogen sulfide, H₂S — poison to you, and a battery to bacteria. Flip the switch below and starve one world to feed the other.
Light is the power source. A leaf takes carbon dioxide and water, spends sunlight, and stores the energy in sugar. Waste product: the oxygen you are breathing.
Hydrogen sulfide is the power source. Bacteria rip electrons out of it and use that energy to build the same sugar. Waste product: little yellow beads of pure sulfur.
This is the whole discovery in one sentence: sunlight is not the only way to make a living. Every textbook on Earth had to add a paragraph.
The star of the vents is Riftia pachyptila, the giant tubeworm — a white leathery tube with a blood-red plume that snaps out of sight when a crab brushes past. It can reach three metres. It grows faster than any other known marine invertebrate: a metre and a half in under two years, from nothing.
And it has no mouth, no gut and no anus. For four years nobody could explain how it fed. Then in 1980 a first-year Harvard graduate student named Colleen Cavanaugh sat in a seminar where Meredith Jones of the Smithsonian mentioned crystals of sulfur inside the worm's tissue — and she stood up and said it out loud: the worms must be farming sulfur-eating bacteria inside their own bodies. She was told to sit down. She was also right, and she proved it in Science the next year.
Roughly one billion bacteria per gram live in an organ called the trophosome, which is most of the worm. The red plume is a chemical lung: its hemoglobin is a rare kind that grabs oxygen and deadly sulfide at the same time without being poisoned, and carries both down to the livestock. The worm is not an animal that eats. It is an animal that gardens.