NASA-supported scientists reported on Tuesday, Sept. 22, 2026, in the journal Cell that an amoeba found in the heated waters of Lassen Volcanic National Park in California can reproduce by division at 145 degrees Fahrenheit (63 degrees Celsius), the highest known temperature limit for eukaryotes. The organism, Incendiamoeba cascadensis, was observed to stop reproducing above that level but to remain active, moving in search of food, at up to 147 degrees Fahrenheit (64 Celsius). The previous limit for eukaryotes, 140 degrees Fahrenheit (60 Celsius), was set by a few species of fungi and red algae.

In laboratory tests, the amoeba remained partially active at 150.8 degrees Fahrenheit (66 Celsius) and recovered after five minutes of exposure to 158 degrees Fahrenheit (70 Celsius), but did not recover from 176 degrees Fahrenheit (80 Celsius). The team sequenced its genome and found genes that help stabilize DNA and maintain protein folding at high temperatures.

Lead author Beryl Rappaport, a graduate student at Syracuse University, said the finding challenges assumptions about membrane stability in complex cells. Alison Olcott, an exobiology program scientist at NASA Headquarters, said such work helps guide the search for life elsewhere. Rappaport cautioned that survival depends on many ecosystem factors beyond temperature, and that Earth remains the only planet known to meet all of the organism's requirements.