Barbecue tongs were the sampling tool. To pull an amoeba out of a narrow geothermal tributary in Lassen Volcanic National Park, a Syracuse University team used extended tools and kitchen tongs to stay clear of near-boiling water, and the organism they brought back divides at 63 degrees Celsius (145 degrees Fahrenheit). The species, Incendiamoeba cascadensis, was described in the journal Cell on September 22, 2026. Its temperature is above the roughly 60 degrees Celsius ceiling long cited for complex cells, which are the eukaryotes: organisms whose DNA sits inside a nucleus, from amoebae and algae to fungi and people. Bacteria and archaea, which lack that nucleus, have long lived in far hotter water, so the record is specific to complex cells.
The name translates roughly as the fire amoeba from the Cascades. Syracuse says the organism came from a narrow geothermal tributary rather than from the park’s famous acidic pools, which is a reminder that the record holder was sitting in a small side stream.
The 63 degree division record
The finding is specific about what the organism does at that temperature. According to Syracuse University’s release, the amoeba thrives at 63 C, surpassing the previous eukaryotic heat-tolerance limit of approximately 60 C. The work was led by Angela Oliverio, an assistant professor at Syracuse, and Beryl Rappaport, a Ph.D. candidate and first author, with collaborators Gordon Wolfe of Chico State and Ken Stedman of Portland State University.
Division is the stricter test than survival or movement. The Sci.News species report lists division at 63 C and motility up to 64 C (147 F), and the EurekAlert release says the organism grew and reproduced at 63 C and survived up to 70 C (158 F) with protective layering. Live Science reported that cells stopped growing below 42 C, went dormant at 70 C and died when exposed to 80 C. Rappaport told the outlet she was very surprised by the result and that the team went back to check that its incubators were calibrated correctly before accepting a division temperature that high, a reminder that the number rests on repeated checks of the equipment as well as on the cells.
Proteins built for heat
The genome offers some explanation. Sci.News reports that the team compared gene activity at 48 C with activity at 61 C and found the amoeba switches on stronger cellular repair systems at the higher temperature. Syracuse’s release says the organism carries extra genes for protein maintenance and DNA repair, and that its proteins contain more positively charged amino acids, a feature it shares with heat-resistant bacteria and archaea.
Rappaport said in the species report that some proteins in Incendiamoeba cascadensis have a high positive surface charge that could help them remain stable. The protein-level analysis also found fewer aggregation-prone patches, the sticky regions where proteins clump when overheated. Sci.News places the species in the Amoebozoa, the large group of amoeboid eukaryotes, and says it is genetically distinct from Vermamoeba vermiformis, a separately named amoeba species. The genetic comparison sits alongside the heat measurements as the basis for describing it as a new species.
The match with bacteria and archaea is the interesting part of the comparison. Microbes in those two groups have long held the world’s heat records, and the work shows a eukaryote reaching for similar tools, namely repair machinery that runs harder when the water is hot and proteins whose charged surfaces keep them folded, without claiming to rewrite the biology of complex cells as a whole.
A tributary near Hot Springs Creek
The organism came from a geothermal tributary of Hot Springs Creek rather than from the park’s famous acidic pools, according to Syracuse. Sci.News says the team sampled there over three years, and that it found matching genetic signatures in geothermal databases from New Zealand and Yellowstone, which would suggest a wider distribution than one creek in California.
Accounts of the prior record differ slightly. Syracuse, EurekAlert and Live Science put it near 60 C, while Sci.News names the amoeba Echinamoeba thermarum at about 57 C as the previous record holder. Both place the new organism several degrees above anything reported before it.
Oliverio told Syracuse that undiscovered eukaryotes may tolerate even higher temperatures, and the Cell paper is titled as setting a new upper temperature limit for eukaryotes. The same release notes that the team hopes the discovery will help identify eukaryotes in extreme environments on Earth and, potentially, on other planets, and that it may have biotechnology uses. Funding came from the National Science Foundation, NASA, the Howard Hughes Medical Institute and a list of international agencies including the European Commission and the Swiss National Science Foundation.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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