Scientists have discovered a previously unknown amoeba in the geothermal streams of California’s Lassen Volcanic National Park that can reproduce at temperatures reaching 145°F (63°C). Named Incendiamoeba cascadensis, the organism has set a new heat-tolerance record for known eukaryotic life. It can remain mobile at approximately 147°F (64°C) and survive brief exposure to even higher temperatures. Published in Cell on September 22, 2026, the study explores how complex cells adapt to extreme heat and offers new insights into the environmental limits of life.
Fire amoeba discovered in California
Researchers collected water and sediment samples from geothermal streams in Lassen Volcanic National Park between 2023 and 2025. They cultivated the microorganisms in a laboratory and examined them under a microscope. Beryl Rappaport, a microbiologist at Syracuse University and the study’s lead researcher, identified an unfamiliar organism displaying characteristic amoeba movement. Further testing established that it was a new species, which the team named Incendiamoeba cascadensis. The name refers to the organism’s heat tolerance and its discovery in the Cascade mountain range region.
Amoeba sets new heat-tolerance record
The researchers observed the amoeba reproducing at temperatures reaching 145°F (63°C). It divides through mitosis, the process in which one eukaryotic cell produces two daughter cells. The discovery extends the known temperature limit for eukaryotic growth, previously estimated at approximately 140°F (60°C). Eukaryotes include organisms such as animals, plants, fungi and many single-celled species whose cells contain a nucleus and specialised internal structures. The amoeba can remain mobile at around 147°F (64°C) and recover after brief exposure to temperatures of approximately 158°F (70°C), although it does not reproduce normally at that temperature.
How the amoeba survives extreme heat
Extreme heat can damage proteins and destabilise cell membranes. To understand how the amoeba withstands these conditions, researchers studied its genome and examined its behaviour at different temperatures. The findings suggest that the organism has adaptations that help protect its proteins and membranes. It can also change its shape and movement patterns in response to rising temperatures. At higher temperatures, the amoeba forms a protective structure that helps it withstand short periods of extreme heat. However, scientists have not yet identified the precise mechanisms responsible for its heat tolerance. Further research will be needed to understand how its cellular components remain stable.
Why bacteria and archaea tolerate higher temperatures
The fire amoeba is the most heat-tolerant known organism among complex life, but some bacteria and archaea can survive at much higher temperatures. These organisms generally have simpler cellular structures and lack a membrane-bound nucleus. Certain archaea found in extreme environments, including deep-sea hydrothermal vents, can grow at temperatures above 100°C (212°F). Comparing these organisms with Incendiamoeba cascadensis could help scientists understand the different ways cells adapt to extreme heat. The amoeba demonstrates that eukaryotic organisms can also develop adaptations that allow them to survive in unusually hot environments.
Discovery may expand research into life’s limits
The discovery could help researchers investigate the limits of life on Earth and guide studies of potential life beyond our planet. Organisms that thrive in extreme conditions are known as extremophiles. Angela Oliverio, a microbiologist at Syracuse University and an author of the study, said the finding highlights the importance of exploring unusual environments. The researchers believe other heat-tolerant organisms may remain undiscovered in geothermal habitats. The amoeba could also provide insights into biotechnology, particularly in the study of heat-stable proteins and enzymes. However, any practical applications would require further research. The team plans to compare the fire amoeba with related species to investigate how its heat tolerance evolved.
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