Scientists discover a eukaryote that thrives at record-breaking 63 °C

A team led by microbiologist Beryl Rappaport collected water from hot springs in California’s Lassen Volcanic National Park and cultured the samples in the lab. When they raised the incubation temperature beyond the previous eukaryotic record of 60 °C, an amoeba continued to multiply at 63 °C, prompting the researchers to name it Incendiamoeba cascadensis, or “fire amoeba” from the Cascades. The organism can survive temperatures as high as 70 °C by becoming dormant and displays protein surface features that prevent heat-induced clumping, a trait shared with extremophilic bacteria and archaea.

It also alternates between a slower, foraging form and a faster, escape-oriented form, likely aiding survival in fluctuating conditions. Published in Cell, the findings challenge the assumed thermal ceiling for eukaryotic cells and hint that even more heat-tolerant species may exist.