New amoeba sets record for heat tolerance in complex life

Researchers at Syracuse University have identified a new amoeba, Incendiamoeba cascadensis, that grows and divides at temperatures up to 63 degrees Celsius (145 degrees Fahrenheit), setting a record for the hottest temperature at which complex life is known to thrive. The findings were published on September 22 in the journal Cell. The organism was collected from geothermal streams in California's Lassen Volcanic National Park between 2023 and 2025. Before the discovery, no eukaryotic cell, meaning a cell with a membrane-bound nucleus, was known to replicate above 60 degrees Celsius (140 degrees Fahrenheit), a limit previously held by certain fungi and red algae. The new record extends that threshold by at least 3 degrees Celsius. In laboratory testing, the amoeba survived brief exposure to 70 degrees Celsius (158 degrees Fahrenheit) by forming a protective cyst and entering a dormant state, recovering when temperatures were lowered. It did not survive heating to 80 degrees Celsius (176 degrees Fahrenheit), and cysts were inactivated above 70 degrees Celsius.