AMOEBA SETS NEW HEAT TOLERANCE RECORD FOR COMPLEX LIFE

NASA-funded scientists have identified a new amoeba species that survives and reproduces at temperatures previously thought impossible for complex life. The organism, found in geothermal streams at Lassen Volcanic National Park in California, has been named Incendiamoeba cascadensis, or the fire amoeba. Researchers observed it dividing at 63°C (145°F), a new upper temperature record for eukaryotes, organisms whose cells contain a nucleus. The findings were published in the journal Cell on Tuesday. Angela Oliverio of Syracuse University, the study's corresponding author, said the discovery pushes the bounds of what was thought possible.

The previous heat limit for eukaryotes stood at 60°C (140°F), held by a handful of fungi and red algae species. Researchers collected samples from 2023 to 2025 from streams reaching up to 64°C (147°F), and the amoeba grew at 57°C in laboratory tests before dividing successfully at 63°C. Above that threshold it stops reproducing but remains active, searching for food at up to 64°C, and can protect itself at up to 70°C (158°F) by changing shape and forming a protective layer. The overall heat record for any organism, 122°C (252°F), belongs to the archaeon Methanopyrus kandleri, found near deep-sea vents.

Scientists study organisms that tolerate extreme heat and other conditions, called extremophiles, to understand the limits of life on Earth and whether similar organisms could exist on worlds such as Mars. Oliverio said there could be other eukaryotes able to survive at even higher temperatures than currently known. Most previous extremophile research focused on bacteria and archaea rather than eukaryotes, and the findings suggest complex cells may be more durable than previously thought. Extremophiles also produce proteins with potential uses in industrial and medical biotechnology, researchers said.