Steamboat's Unique Cave Worms Officially Have A Name: Limnodrilus Sulphurensis

Jun 14, 2016

Native American legends spoke of a gateway to the underworld, with noxious clouds of steam spewing from the Earth. Humans would pass out in a few minutes if they enter the cave because of the lethal levels of hydrogen sulfide and carbon dioxide. Located on the side of Steamboat Springs' Howelsen Hill, the ancient cave was formed by hot spring water flowing through the travertine rock.

This dark, slimy, stinky site -- Sulphur Cave Spring -- is also the only place in the world a new species of tiny worms have been found.

About an inch long, with transparent body segments, the worms are the thickness of pencil lead. David Steinmann, research associate of the zoology department at the Denver Museum of Nature & Science first discovered the worms when he crawled into Sulphur Cave Spring in 2007.

The cave trip was because of a tip from his caving friends, who had a hunch a new species was waiting to be discovered there.

“It’s a very unusual environment, I went in looking for a new species of invertebrate or insect, so the purpose of my visit was to look for a new species.”

David Steinmann in SCBA gear, emerging from Sulphur Spring Cave with the worms in his right hand.
Credit Sherecee Steinmann

It took over eight years of work to formally describe and name them -- Limnodrilus sulphurensis -- as noted in the scientific journal Zootaxa [.pdf]. A genetic analysis by Dr. Christer Eseus found that the worms are a distinct new species found only in Steamboat Springs, Colorado.

Steinmann, an avid caver, used a self-contained breathing apparatus in order to go into Sulphur Cave Spring.

“As I went in and my wife Debbie was behind me, I immediately noticed in the little stream in the cave little masses of red worms wiggling around and large clumps of worms on the floor of the cave. They are pretty small, but there are thousands of worms.”

The cave isn’t the only place in Steamboat Springs that Steinmann has found the worms. He thinks they may live in the bedrock caves beneath the town, but by far the largest concentration is in the sulphur cave.

“Something prehistorically must have been able to move into the water of Sulphur Cave and somehow adapted - maybe living in an area where there is more freshwater meeting the hot springs habitat and continued to adapt to the sulphurous environment,” said Steinmann, who thinks the worms evolved from similar species that are found in Colorado’s streams and lakes.

Worm experts aren’t sure why they cluster together. It’s a very unusual behavior for worms. Steinmann said it may be because they have no discernible predators, or it’s a mating behavior.

Their hemoglobin rich blood gives these new worms a dark red color and may be the key to medical benefits for humans. A group of scientists in France are studying extremophile worms for a new antibiotic. Steinmann will be collaborating and sending them the sulphur cave worms to aid their research.

Even for worms, Steinmann said those found in Sulphur cave bind oxygen extremely well. Long-term medical benefits for people with circulatory problems for example, could be derived from their blood.

“These worms have an extremely unusual network of capillaries and blood vessels at the surface of their skin that is very complicated and dense that helps them absorb oxygen from the water in their cave environment.”

Steinmann cautions people not to go into Sulphur Cave Spring because of the air’s toxicity, but he plans to go back and look for other potential new species that might be waiting in its depths.