SCIENCE

Scientists have extracted long-dormant microbes from inside the famous giant crystals of the Naica mountain caves in Mexico—and revived them. (BBC)

Where else have ancient microbes been found?

Teachers, scroll down for a quick list of key resources in our Teachers Toolkit, including a link to today’s simple MapMaker Interactive map.

Discussion Ideas

• Scientists are excited about the extremophile microbes just discovered at the “Cave of the Crystals” in Naica, Chihuahua, Mexico. What are extremophiles?
  • Extremophiles are organisms adapted to survive in very harsh (extreme) environments.
    • Extremophiles have been discovered in environments such as toxic ocean vents, burning natural gas fires, Antarctica’s frigid desert “lakes,” and even outer space.

• What conditions make the cave system beneath Naica so extreme?
  • The Naica caves are hot, humid, acidic, and dark.
    • The temperature ranges between 40° and 60°Celsius (104° to 140°Fahrenheit), with spikes up to 70°C (158°F).
    • Humidity ranges between 90% and 99%.
    • The bacteria that may have helped form the cave secrete sulfuric acid as they eat away at limestone.
    • No light penetrates the cave, located about 300 meters (980 feet) below ground. This means no photosynthesis can take place—no plants, no food as we know it.

• How did the microbes in the Cave of Crystals adapt to its extreme conditions?
  • The microbes are chemosynthetic, meaning they obtain energy from chemicals in their dark, hot, rocky surroundings. Scientists think the microbes exist by processing minerals such as iron and manganese.

• Scientists studying the cave are not chemosynthetic! How do they conduct long-term studies of the cave?
  • Over very short periods of time. Scientists can only stay in the cave for about 30 minutes, and wear respirators and “ice suits” (vests with ice packs sewn in).

• The BBC article mentions three discrete type of microbial communities discovered in the Cave of Crystals: bacterial, archaean, and viral. What organisms are present in each of these communities?
  • bacteria. Bacteria are either single-celled or multi-celled microbes, and they’re prokaryotic—their cells have no nucleus and lack membrane-bound organelles. They’re shaped like rods, cones, plates, or coils. They have flagella, thread-like structures that allow them to move. Bacteria are among the most common organisms on Earth.
  • archaea. Archaea look a lot like bacteria—they’re single-celled prokaryotes that come in similar shapes and also have flagella. Archaea are profoundly different from bacteria, however: their genetics and chemical protein structures are very, very distinct. Distinct enough that in many “trees of life”, bacteria and archaea are two of the three major branches on the tree. (The third, the eukaryotes, are all organisms whose cells have discrete organelles. That includes us. Archaea and bacteria are, in many ways, as different from each other as they are from us.)
  • viruses. Unlike bacteria and archaea, viruses are not organisms. They are pathogenic agents that live inside organisms. The viral communities in the Cave of Crystals are actually inside the bacteria or archaea.

• The scientist who made the announcement about the microbes in the Cave of Crystals is the director of NASA’s Astrobiology Institute. What is an astrobiologist? Why would astrobiologists be interested in tiny cave-dwellers on Earth?
  • Astrobiologists study environmental conditions and adaptations that may make life possible in outer space.
  • Astrobiologists are extremely interested in extremophiles. They have studied ocean vents, Antarctic valleys, and even the toxic environment of Chernobyl to study how organisms can adapt to seemly harmful conditions. “The astrobiological link is obvious in that any extremophile system that we’re studying allows us to push the envelope of life further on Earth, and we add it to this atlas of possibilities that we can apply to different planetary settings.”

TEACHERS TOOLKIT

BBC: Naica’s crystal caves hold long-dormant life

Nat Geo: Water Trapped for 1.5 Billion Years Could Hold Clues to Ancient Life study guide

Nat Geo: Where is the Cave of Crystals? map

Nat Geo: Cavern of Crystal Giants article

NASA: Astrobiology Institute