In 1977 we found thriving life on the seafloor with no sunlight

In February 1977, a team aboard the research submersible Alvin dropped into the dark of the Galápagos Rift to study geology — temperature spikes hinted at hot springs on the seafloor. What they found instead rewrote biology. Clustered around the vents were dense thickets of giant tube worms, white clams the size of dinner plates, and ghostly crabs, kilometers below any sunlight. The crew was so unprepared that no biologist was even aboard; they preserved the first specimens in vodka because that was the only suitable fluid on the ship.

These hydrothermal vents spew mineral-rich water heated by magma, and the food web here owes nothing to the Sun. Microbes use chemosynthesis — harvesting energy from chemicals like hydrogen sulfide in the vent fluid — and everything else feeds on them. The signature animal, the red-plumed Riftia tube worm, has no mouth, no gut, and no anus. It survives entirely on symbiotic bacteria packed inside a special organ, feeding them sulfide carried in by its blood and living off the organic compounds they make in return.

The most dramatic vents, the black smokers found soon after, gush water near 400°C (750°F) that doesn’t boil because the crushing pressure holds it as a superheated liquid.

The discovery did more than reveal a new ecosystem. It put hydrothermal vents at the heart of origin-of-life theories, since these chemical-rich, energy-soaked cracks may be where life first assembled. And it reframed the hunt for life beyond Earth: the subsurface oceans of Jupiter’s moon Europa and Saturn’s Enceladus could host vents of their own, warm seams of chemistry in worlds that never see the Sun.