#SoCaltech: Tristan Caro

“I study microbes that live in some of the most extreme environments on Earth—volcanoes, permafrost, deep underground.

I had the opportunity to work with an incredible team of cave explorers and scientists inside the crater of Mt. St. Helens this past August. We flew by helicopter into the crater and landed on the glacier housed within. There, we explored ice caves formed by volcanic heat coming up from below—meltwater was pouring down continuously. The crater walls are unstable, and every few minutes you could hear the cracking sounds of rocks and mini landslides tumbling down. The whole place had this quality of being both fragile and threatening at the same time. But what struck me most was the life. This is a place that was essentially wiped clean by the eruption, and yet microbes have made it home. It’s humbling to know that there’s an entire ecosystem quietly rebuilding itself in one of the most hostile places on the continent. That’s when the work really hits you. It’s not just the science, but the sense that we’re still finding out how much life is capable of. Many of the tools we take for granted in biology came from extremophiles first, created by organisms that have been quietly perfecting them for millions of years in places nobody thought to look.

I truly enjoy working in this field and its capacity to excite and motivate student inquiry. For the Mt. St. Helens project, I had the opportunity to loop in amazing graduate students—Zahra Shivji, Grace Solini, Sarah Garzione—each with their own thesis projects and skillsets. Together, we’ve developed a truly collaborative research angle as a lab. It’s a really unique opportunity—far from the dreaded ‘group project’ of undergrad classes, this Mt. St. Helens study is a wonderful example of how collaborative science creates a team that is more than the sum of its parts.”

Tristan Caro is a Foster & Coco Stanback Postdoctoral Scholar and Research Associate in geobiology at Caltech, in the laboratory of Smruthi Karthikeyan, Gordon and Carol Treweek Assistant Professor of Environmental Science and Engineering and William H. Hurt Scholar. In 2025, he and a team of collaborators conducted a research expedition to study extremophiles at Mt. St. Helens.

#SoCaltech is an occasional series celebrating the diverse individuals who give Caltech its spirit of excellence, ambition, and ingenuity. Know someone we should profile? Send nominations to magazine@caltech.edu.