The Blood-Red Worms from Sulphur Cave

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A new species of worm was discovered at a toxic cave in Steamboat Springs, Colorado by David Steinmann, Research Associate of the Zoology Department at the Denver Museum of Nature & Science. The unusual worms were named Limnodrilus sulphurensis in the scientific journal Zootaxa, with the name being chosen by Steven Fend of the U.S. Geological Survey. Scientists from the United States, Germany, and Sweden collaborated to describe the new worm species. Genetic analysis by Dr. Christer Erseus confirmed that the cave worms are a distinct new species, currently only known from Steamboat Springs. The worms live in a very hostile environment, thus they are extremophiles.

When David Steinmann first crawled into Sulphur Cave during the summer of 2007, he immediately noticed numerous clumps of bright red, blood-colored worms living in the small stream that flows through the cave. He suspected that the worms could be a new species previously unknown to science, and after over 8 years of work the worms are now formally described and named. The worms are small, about an inch long and as thin as a pencil lead, with transparent body segments. Their blood has hemoglobin that binds oxygen amazingly well since they live in a low oxygen environment. The new Limnodrilus sulphurensis worms are now part of the permanent collections at the Denver Museum of Nature & Science, being housed with over one million other Zoology Department specimens in the state-of-the-art Avenir Collections Center.

Sulphur Cave is wet, muddy, slimy and stinky, smelling like rotten eggs. Native American legends spoke of the cave as a sacred and ceremonial place, being a gateway to the underworld. The entrance is dark and foreboding, spewing noxious clouds of steam into the air. There are lethal levels of toxic gases inside the cave, with hydrogen sulfide and carbon dioxide at concentrations that can cause a person to pass out after a few breaths, which could be followed by death. Acid drips on the cave ceiling will burn holes in one’s clothes, and the cave is too low for standing in most areas. Yet inside Sulphur Cave there exists a unique ecosystem teeming with worms, spiders, flies, beetles, springtails, and millipedes that can somehow survive the harsh conditions.

Steinmann uses special equipment and SCBA (Self-Contained Breathing Apparatus) to safely enter Sulphur Cave.  A rescue team stands by to assist incase a problem were to occur. David is a member of the National Speleological Society and he has been researching cave life for over 20 years. The City of Steamboat Springs owns Sulphur Cave and permission was obtained to enter and study the cave. People should not attempt to enter Sulphur Cave.

Knowing that worms and other creatures can thrive in such an inhospitable place is an amazing testament to the tenacity of life. Dr. Olav Giere, who is an expert on extreme aquatic habitats at the University of Hamburg in Germany, noted that the hydrogen sulfide levels in the Sulphur Cave stream are 10 times higher than those found at deep sea volcanic vent ecosystems. The Sulphur Cave worms survive by eating sulfur oxidizing bacteria. These worms do not depend upon the sun’s energy to live, they are part of a chemotrophic ecosystem based upon the oxidation of hydrogen sulfide. Similar ecosystems could potentially exist on other planets like Mars, or even in other solar systems, where isolated caves may harbor unknown species of living organisms. Further studies regarding the remarkable adaptations of these incredible worms are continuing in both Europe and at the Denver Museum of Nature & Science.

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