Life in Lava Tubes

Standing in one of Hawaii’s caves, you might think it’s empty. It’s dark. It’s quiet. Not many plants or animals call this place home. But there’s a lot of life. Most of it you just might not notice.

There might be patches of gold, silver, tan, or pink on the cave walls. These splotches of color consist of microbes × microbe a microscopic organism (noun) .

Scientists have been studying these microbes. One reason is that some might be similar to life that once lived on Mars—and maybe still does.

Under the Surface

Many of Hawaii’s caves are lava tubes. They were formed by volcanic activity. After an eruption, hot lava flows like a river. Air cools it. The surface hardens into black basalt rock. But underneath, molten lava might still flow. It drains away below the basalt. This leaves behind an empty tube, or cave.

LIKE A RIVER Hot lava flows after an eruption. As it cools, the surface hardens to a black rock called basalt. If lava continues to flow underneath, a lava tube will be left behind.

There are lava tubes on Mars, too. So scientists wonder: Do rock-loving microbes also exist there? Hawaiian caves might unlock what life could be like on other worlds.

“It’s a good place to start,” Rebecca Prescott told TIME for Kids. She’s an astrobiologist × astrobiologist a scientist who studies the possibility of life on other planets (noun) at the University of Mississippi. She’s part of a team of scientists. They’ve been looking at microbes in Hawaiian caves.

Microbial Cities

Cave microbes have their own ways of surviving their environment. Some get energy from “eating” the rocks (see “Martian Gardens”). Many of these species are ancient, allowing scientists to understand how microbes lived billions of years ago. “When you walk into a lava cave,” Prescott says, it’s like you’re walking back n time.”

Scientists are now learning how groups of microbes communicate. Microbes grow in communities. The organisms within a community can “talk” to one another by sending out chemical signals.

SLIMY CITIES This microbial community, known as biofilm, is growing on the walls of a cave near the Kilauea volcano, in Hawaii.

And microbe communities might communicate with one another, too. This might help them survive. Prescott and her team hope to learn this microbial language and how it helps these tiny cities thrive—on Earth, and perhaps beyond. 

Martian Gardens

Microbes might be important team members on future Mars missions. A one-way trip to the Red Planet could take eight months. Astronauts might need to grow their own food. But not many plants can grow in the planet’s rocky red dirt. Microbes might help.

Here on Earth, some microbes break down toxic chemicals in dirt. Others can “eat” rocks. This releases nutrients to make soil more friendly to plants. Scientists think that microbes can do the same on Mars, helping turn the rocky dirt into rich soils where Martian gardens can grow.