Earth Notes
1:47 pm
Wed May 26, 2010

Earth Notes - Lava Tubes

Flagstaff, AZ –
Pitch black and cool year round, lava tube caves might seem like an inhospitable place to call home. But scientists are discovering that lava tubes shelter a surprising variety of organisms, some of which live nowhere else on earth.

A lava tube forms when molten lava flows over the ground, then cools and hardens from the outside in. The hotter, inner lava flows away and leaves behind a tube-like cavern. Lava River Cave near Flagstaff, the longest known lava cave in Arizona, stretches a mile underground.

For the past several years, scientists have explored lava tubes in Arizona and New Mexico to learn about the organisms that live in this unlikely habitat. A research team from Northern Arizona University and the U.S. Geological Survey has discovered 15 new species of invertebrates in lava tubes and other southwestern caves.

Many animals find shelter in lava tubes from eyeless millipedes to amphibians and bats. But it's the smallest organisms that are making big news these days. Scientists in New Mexico recently reported that colorful deposits on the walls of lava tubes, once thought to be minerals, are actually the waste products of microbes that feed on minerals in the volcanic rock.

This discovery may have implications far beyond the Four Corners region. Unlike most habitats found on Earth, lava tubes exist on other planets. On Mars, where surface conditions fluctuate between inhospitable extremes, lava caves offer a protected, stable environment, and possibly a good place to search for evidence of extraterrestrial life.