Ancient Lava Caves in Hawai'i Are Teeming With Mysterious Life Forms

Microbes are the smallest known living organisms on Earth and can be found just about everywhere, even in the cold, Mars-like conditions of lava caves. From a report: On the island of Hawai'i, scientists recently found a marvelous assortment of novel microbes thriving in geothermal caves, lava tubes, and volcanic vents. These underground structures were formed 65 and 800 years ago and receive little to no sunlight. They can also harbor toxic minerals and gases. Yet microbial mats are a common feature of Hawai'ian lava caves. Samples of these mats, taken between 2006 and 2009 and then again between 2017 and 2019, reveal even more unique life forms than expected. When researchers sequenced 70 samples for a single RNA gene, commonly used for identifying microbial diversity and abundance, they could not match any results to known genuses or species, at least not with high confidence. "This suggests that caves and fumaroles are under-explored diverse ecosystems," write the study's authors. e biomass in Earth's deep subsurface. Yet because these organisms are so tiny and live in such extreme environments, scientists have historically overlooked them. In recent years, underground microbes have received more interest because they exist in environments very similar to those found on Mars. But there's still a long way to go. Recent estimates suggest 99.999 percent of all microbe species remain unknown, leading some to refer to them as "dark matter." The new research from Hawai'i underscores just how obscure these life forms are.

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