Science Friday

‘Fire Amoeba’ Likes It Hot, And A Faraway Lava Planet

December 18, 2025

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  • Researchers discovered *Incendiamoeba cascadensis*, a eukaryotic amoeba capable of movement and division at 145 F (63 C), setting a new survival record for its cell type, found in a stream in Lassen Volcanic National Park. 
  • The 'fire amoeba' survives extreme heat partly through genetic adaptations related to thermal stress signaling and proteostasis, and by rapidly shape-shifting between a worm-like form and a 'blob' form to escape heat. 
  • Exoplanet TOI-561b, a hot, rocky world orbiting its star in less than a day, shows the strongest evidence yet of an atmosphere on a rocky exoplanet, potentially suggesting a secondary atmosphere formed from outgassing despite its extreme proximity to its star. 

Segments

Sponsors and Introduction
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(00:00:00)
  • Key Takeaway: The Science Friday episode begins with sponsor messages before introducing the main topics.
  • Summary: The episode opens with advertisements for Alienware, the New York Hall of Science, and Northwell Health. Host Flora Lichtman then introduces the first segment concerning the ‘fire amoeba’ discovery.
Discovery of Fire Amoeba
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(00:01:42)
  • Key Takeaway: A new eukaryotic amoeba, Incendiamoeba cascadensis, was found in a stream in Lassen Volcanic National Park surviving at 145 F.
  • Summary: The amoeba was discovered after researchers incubated a water sample from a seemingly unremarkable, pH-neutral stream near Boiling Springs Lake. This organism is the new survival record holder for a eukaryotic cell, thriving at temperatures previously thought too high for such life.
Mechanisms of Heat Tolerance
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(00:04:22)
  • Key Takeaway: The amoeba’s heat tolerance is linked to elevated genes for thermal stress and proteostasis, and rapid shape-shifting abilities.
  • Summary: Genome sequencing revealed elevated numbers of genes related to proteostasis, the cell’s system for ensuring proteins are synthesized and folded correctly. The amoeba can quickly switch between a long, skinny worm-like form and a classic blob form, hypothesized to allow faster escape from rising temperatures. Furthermore, forming a cyst allows the organism to survive temperatures as high as 70 C (158 F).
Impact on Extremophile Science
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(00:08:18)
  • Key Takeaway: The existence of this amoeba challenges the long-standing scientific paradigm that eukaryotic life cannot grow above 60 degrees Celsius.
  • Summary: The previous paradigm, established since the 1970s, held that no organism could grow above 60 degrees Celsius. This discovery opens new questions regarding the theoretical upper temperature limit for eukaryotic life and the underlying mechanisms that allow it.
Sponsors and Lava Planet Tease
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(00:09:37)
  • Key Takeaway: The segment concludes with a transition to the second topic: a faraway lava planet observed by JWST.
  • Summary: Following the discussion on the ‘fire amoeba,’ the host teases the next segment about a fiery planet where the ground is lava. The show then breaks for sponsor messages from ATT and Bayer.
Exoplanet TOI-561b Characteristics
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(00:10:59)
  • Key Takeaway: Exoplanet TOI-561b orbits its star in just 0.4 days and is twice the age of our solar system, exhibiting a surprisingly low bulk density.
  • Summary: TOI-561b is a ‘wet lava ball’ orbiting a star that is older and has less iron but more rock-forming elements than our sun. Its extremely short orbital period suggests it might have migrated inward recently, potentially bringing an atmosphere with it.
Atmosphere Detection on Lava World
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(00:11:07)
  • Key Takeaway: The James Webb Space Telescope provided the strongest evidence yet for an atmosphere on a rocky exoplanet, despite the planet’s extreme heat.
  • Summary: The planet’s day-side temperature is cooler than expected for a bare rock, indicating the presence of an atmosphere, ruling out a purely rock-vapor atmosphere. While the exact composition is unknown, possibilities include water or carbon dioxide, as the atmosphere appears to be secondary, formed from outgassing from the interior.
Significance of Secondary Atmosphere
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(00:18:43)
  • Key Takeaway: Studying the secondary atmosphere of TOI-561b offers a rare glimpse into the interior composition of distant rocky planets.
  • Summary: Although TOI-561b is uninhabitable, analyzing its atmosphere provides insight into the planet’s interior structure, which is otherwise difficult to ascertain for such distant worlds. This observation helps scientists understand how rocky planets acquire and retain atmospheres.
Episode Wrap-up and Credits
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(00:20:18)
  • Key Takeaway: The episode concludes with production credits, listener engagement prompts, and final sponsor messages.
  • Summary: The episode credits Charles Berquist as the producer and encourages listeners to leave reviews or call the listener line. Final sponsors include LifeLock and TurboTax.