In February 1977, the Alvin—a submersible big enough for three people, provided none of them stretched out their arms—dove to the bottom of the ocean, just north of the Galapagos Islands. The scientists who had crammed themselves into the sub were expecting to find hydrothermal vents—hypothetical sites where superheated water belched forth from the Earth’s interior. And they succeeded. But to their shock, they also discovered life, in extreme and implausible abundance.

At a depth of 2,400 meters, in pitch-black waters that were disconnected from the sun’s energy and compressed by the full pressure of the overlying ocean, the Alvin crew found what they described as a “Garden of Eden.” Clams and shellfish clung to the belching chimneys of rock. Crabs clambered over them and fish swam past. And strangest of all, giant worms encrusted the vents in stony tubes of their own making. Their scarlet gills protruded from these cylinders like tubes of lipstick—beautiful, if eerily so.

That life existed here at all, let alone in such wealth, was extraordinary. The crew, all of whom were geologists, were so unprepared for such a find that they hadn’t brought any biologists with them. And when they returned to the surface, the only substance they had for preserving the specimens they had collected was vodka.

Those vents, and others like it, have changed our understanding of the extreme conditions in which life could thrive. And the giant tube worms led to the discovery of an entirely new way of life—one that relies entirely on microbes, and that allows creatures to eat even though they’re mouthless and gutless. It’s called chemosynthesis, and its story is told in the video below—the third in a series of online films produced by HHMI Tangled Bank Studios, which adapt the stories in my book, I Contain Multitudes.