Deep Sea Microbiology (UNSEEN OCEAN CRITTERS) with Peter Girguis

“I picked up a rock from the sea floor one time with the Alvin sub because I said, ‘Oh, this was really shiny.’ … It was so young that it was still popping and had little gas inclusion. So it sounded like Rice Krispies.” That is one way to describe your first encounter with a newborn piece of the Earth’s crust. Harvard professor and deep-sea microbiologist Peter Girguis spends his time figuring out how the tiniest organisms on the planet make a living in its most extreme, inaccessible places — and the answers are stranger and more consequential than most of us realize.

The Vast, Dark Living Space We Ignore

When we think of Earth’s habitable zones, we picture forests, plains, coral reefs. But Girguis points out a staggering fact: everything we consider “normal” — the Amazon, the Serengeti, Los Angeles, Boston — occupies only 20% of the planet’s cubic living space. The other 80% is deep, dark ocean, below a thousand meters, where sunlight never reaches. “Our planet is primarily fueled by a star,” he says, but down there, that fuel runs out. Most deep-sea life depends on “marine snow” — a constant drizzle of poop, dead algae, fish scales, and snot that sinks from the sunlit surface. It’s a buffet line: the surface dwellers get the shrimp and lobster, the midwater creatures get the tenderloin, and by the time you reach the abyss, you’re scraping the bottom of the chafing dish