Meet the ‘Fire Amoeba,’ a Newfound Blobby Organism That’s Defying Expectations About How Much Heat Complex Life Can Handle

The newly described species, found in Northern California’s Lassen Volcanic National Park, can still reproduce at 145 degrees Fahrenheit and move around at 147 degrees, according to a new study

Margherita Bassi | Daily Correspondent

September 28, 2026 10:00 a.m.

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Northern California’s Lassen Volcanic National Park features wildflower meadows, mountain lakes and volcanoes—and, according to new research, a record-breaking organism.

Its hot springs are home to a newly identified single-celled organism that’s redefining the heat limits of complex life. An amoeba named Incendiamoeba cascadensis—which means “fire amoeba of the Cascades”—can survive and swim around at a sweltering 147 degrees Fahrenheit, researchers report in the journal Cell on September 22. Discovering such endurance here on Earth broadens the map of where scientists might search for life elsewhere in the universe, too.

“I was very surprised,” study co-author Beryl Rappaport, a microbiologist at Syracuse University, tells Live Science’s Skyler Ware. “We definitely had to go back and check to make sure that our incubators were calibrated correctly. … It really was amazing.”

Life as we know it falls under one of two categories: prokaryotic or eukaryotic. Prokaryotes are simple, single-cell organisms that lack a nucleus and other membrane-bound organelles. They were probably Earth’s first life forms, and today, they include bacteria and archaea. Eukaryotes, on the other hand, are more complex organisms with cellular organelles, such as mitochondria to provide energy and a nucleus to store genetic material. This class includes a wide range of beings, including humans, plants and single-celled algae.

Some prokaryotes are known to survive in extreme environments and are aptly called extremophiles. The archaeon Methanopyrus kandleri, for example, can endure temperatures up to 252 degrees—and is the reigning champ for heat tolerance among all life.

Less research has been conducted on heat-loving eukaryotes. That’s partly because their biomolecules and membranes usually break down in scorching conditions. In fact, researchers had previously suggested that eukaryotes’ organelle membranes couldn’t remain stable above 144 degrees—but the new research shows that at least one species is tougher than they thought.

In the new study, Rappaport and colleagues used long barbecue tongs to dunk vials into steaming water from geothermal springs at Lassen Volcanic National Park, Ari Daniel reports for NPR. They brought the samples to the lab and saw that the water contained amoebas. So, the team grew the organisms and subjected them to all sorts of tests.

“We set up cultures at a few temperatures, with the hottest being 57 degrees Celsius [135 degrees Fahrenheit] because that is the highest temperature previously described for an amoeba,” Rappaport tells Science News’ Jake Buehler.

I. cascadensis was doing just fine, so the team cranked up the heat. At 145 degrees, the amoeba still replicated. Above that temperature, it stopped reproducing but continued moving around at up to 147 degrees, blowing past the previous eukaryotic record of 140 degrees, set by some species of fungi and red algae.

“I think the most significant implications of this research is that it challenges our understanding of how and where eukaryotic life can persist,” study co-author Angela Oliverio, a microbiologist at Syracuse University, tells Reuters’ Will Dunham. “That has implications for understanding evolutionary biology in terms of fundamental constraints on complex cells and how they can evolve, and it expands the search for life on Earth and elsewhere in the universe.”

The team also examined the organism’s complete set of genetic instructions and investigated which genes turned on at various temperatures. Analyses revealed some genes that protect and stabilize DNA, some that enable the organism to sense its external environment, and some that help maintain proper protein folding when exposed to heat.

What’s more, comparing I. cascadensis’ genetic code to DNA found in other geothermal waters hints that relatives of the fire amoeba might be residing in places including New Zealand and Yellowstone National Park.

“By looking in an unusual place, the study team found unusual life,” Adrienne Kish, a microbiologist at the National Museum of Natural History in Paris who did not participate in the study, tells the New York Times’ K. R. Callaway. That means we need to continue exploring our planet, she adds. “There is so much more to be found as we find new ways to access and study extreme environments.”

Margherita Bassi is a freelance journalist and trilingual storyteller. Her work has appeared in publications including BBC Travel, Discover magazine, Live Science, Atlas Obscura and Hidden Compass.