Small Creature Living in Volcano Sets New Heat Record

Some organisms thrive in extreme heat, but the title for the ultimate heat lover belongs to a tiny, wriggling organism called the fire amoeba of the Cascades, scientifically named Incendiamoeba casadensis. This microscopic eukaryote was recently found in the hot springs of Lassen Volcanic National Park and can grow and reproduce at temperatures reaching 145F. Remarkably, it doesnt begin growing until temperatures climb above 107F.

Described in a recent scientific preprint, this organism challenges long-held assumptions about the environmental limits for complex life and where such life can exist. While humans and most Earthly life thrive around 68F, some extremophiles inhabit much hotter settings, including volcanic vents, geothermal pools, and arid deserts. Unlike most heat-loving extremophiles, which are primitive prokaryotes like bacteria or archaea, the fire amoeba is a eukaryote, complete with nuclei and organellesstructures typically vulnerable to high temperatures.

To understand the organisms heat tolerance and survival strategies, researchers collected samples from the hot springs and experimented with growth across 17 temperature settings, ranging from 86F to 147F. They discovered that the fire amoeba forms protective cysts at around 151F, entering a dormant state, and ceases growth entirely at 176F.

Genomic analysis revealed that the fire amoeba possesses enhanced repair and quality control systems, including specialized proteins that endure heat stress and additional enzymes that dismantle damaged proteins. It also has an increased number of genes dedicated to DNA repair and environmental sensing, including temperature changes.

Researchers suggest that other heat-adapted amoebas may yet be found, meaning Incendiamoeba casadensis may not retain its crown as the planets most heat-tolerant eukaryote indefinitely.

Author: Sophia Brooks