Fire Amoeba Defies Biology’s Hard Limit

Scientists in lab coats reviewing data on a computer — Photo: Alexander Raths / Shutterstock

Scientists have found a tiny living cell that can grow and multiply in water hot enough to make coffee.

Quick Take

A newly named amoeba, Incendiamoeba cascadensis, divides at 145°F (63°C) and stays active up to 147°F (64°C).
The organism lives in a hot spring at Lassen Volcanic National Park in California.
It breaks the old heat record for eukaryotes, the group of complex cells that includes animals, plants and fungi.
Syracuse University researchers, supported by NASA funding, led the discovery and published it in the journal Cell.
The find could change how scientists search for life on other planets and moons.

A Fire-Loving Amoeba Rewrites the Rules

Researchers found the amoeba in a steaming stream near Lassen Volcanic National Park. They named it Incendiamoeba cascadensis, which means “fire amoeba of the Cascades.” The single-celled creature can divide through mitosis, the process cells use to multiply, in water as hot as 145.4°F (63°C). It stays alive and searches for food up to 147.2°F (64°C).

That number matters because scientists had long believed 140°F (60°C) was the hard ceiling for eukaryotes. Only a handful of tough fungi and red algae could handle temperatures near that limit. Most complex cells, including other amoebas, were thought to max out around 135°F (57°C). This new amoeba shattered both of those old boundaries by several degrees.

Why Extreme Heat Usually Kills Complex Cells

Eukaryotic cells carry a nucleus and other complex parts, along with membranes that hold everything together. High heat makes those membranes unstable and breaks apart the proteins cells need to survive. That is why bacteria, which lack these delicate structures, have always dominated the hottest known environments on Earth. The fire amoeba appears to have found a way around that biological weak spot.

Beyond just surviving, the amoeba can protect itself even further. Researchers found it can withstand temperatures up to 158°F (70°C) by changing its shape and building a tough protective covering around itself. Angela Oliverio, a Syracuse University biology professor who helped lead the study, and graduate student Beryl Rappaport documented the behavior after collecting samples from the park’s geothermal waters.

What the Discovery Means for the Search for Life

NASA funded part of the research because extremophiles, organisms that thrive in harsh conditions, help scientists understand where life might exist beyond Earth. If complex life can survive water this hot on our planet, similar organisms could potentially survive in hot environments on other worlds. That includes places once considered too extreme to support anything more complex than basic microbes.

This little thing can live at 145°F.

Meet the “fire amoeba.”

Scientists studying Incendiamoeba cascadensis, found in California’s Lassen Volcanic National Park, discovered it can reproduce at temperatures up to 145°F.

It can even survive brief exposure to temps of up to 158°F… pic.twitter.com/p9wNvprP4D

— BluByU (@Udntnonutn) September 22, 2026

The study appeared in the journal Cell, and the underlying research data has also circulated through preprint servers, letting other scientists review the methods behind the record claim. Separate research on the theoretical limits of eukaryotic heat tolerance suggests no complex cell can complete a full life cycle above about 149°F (65°C). If that ceiling holds, the fire amoeba sits remarkably close to the true outer edge of what complex life can endure.

The discovery adds a new name to the short list of organisms that push biology’s boundaries. Scientists say the amoeba nudges the known heat limit for complex cells up by roughly five degrees compared to the next toughest species on record. For a field built on decades of assumed limits, that shift counts as a significant and well-documented breakthrough.