Newfound 'fire amoeba from the Cascades' sets record for the hottest temperature complex life can survive at

A newly-discovered amoeba has set the record for the hottest temperature at which complex life can thrive.

The amoeba, found in Lassen Volcanic National Park in California, grows and divides at temperatures up to 145 degrees Fahrenheit (63 degrees Celsius) and can survive brief stints in up to 158 F (70 C) environments, a new study finds. Prior to the discovery, no complex cells were known to replicate at temperatures above 140 F (60 C).

"I was very surprised," study first author Beryl Rappaport , a microbiologist at Syracuse University in New York, told Live Science. "We definitely had to go back and check to make sure that our incubators were calibrated correctly … It really was amazing."

Amoebas are single-celled organisms that move by pulling themselves forward with tendrils of cellular fluid. They are eukaryotes , which means they store their DNA inside a membrane-bound nucleus. Amoebas are neither plants, animals nor fungi, but they are more complex than prokaryotic organisms such as bacteria and archaea, which have no nucleus.

Past research had suggested that amoebas could thrive in warm geothermal springs, Rappaport said, but few of these organisms have been studied in laboratories. To investigate, Rappaport and her colleagues travelled to Lassen Volcanic National Park to collect and study these heat-loving creatures.

The team discovered the newfound amoeba in samples collected along a tributary of Hot Springs Creek inside the park. Dubbed Incendiamoeba cascadensis , or "fire amoeba from the Cascades," the species thrive at temperatures between 131 and 135 F (55 and 57 C). In fact, they stopped growing below 108 F (42 C), indicating that the amoebas need high temperatures to flourish.

Using a heated microscope that kept the amoebas toasty, the scientists watched the cells divide and replicate at temperatures as high as 145 F (63 C) — the highest temperatures known for eukaryotic cells (although prokaryotes have been known to survive temperatures as high as 250 F, or 122 C).

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