This Eight-Day Festival Celebrates One of Alaska’s Weirdest Worms

Welcome to the Cordova Ice Worm Festival, a quirky local tradition honoring the mysterious creatures that live in glacial ice

iceworms on a glacier
Ice worms spend most of the day burrowing their way through the cold, dark interior of the glacier, coming to the surface only in the afternoon to feed on algae and bacteria. Scott Hotaling

Wander onto a southern Alaskan glacier on a summer day around 4 p.m., and you’ll likely witness a mysterious phenomenon that few people know exists: the rising of the ice worms.

Ice worms are about an inch long and pitch-black. They look a bit like small earthworms, and they’re the only macroscopic animals adapted to live inside glacial ice. They spend most of the day burrowing their way through the cold, dark interior of the glacier, coming to the surface only in the afternoon to feed on algae and bacteria. When that happens, they pop out of the snow by the million. With up to 50 ice worms per square foot, you can’t walk without stepping on them.

It’s a fascinating spectacle, one that even scientists don’t fully understand. The habits of ice worms are poorly understood. Most people—even those who have spent their whole lives in the Pacific Northwest, where ice worms live—have never heard of them.

But in one small fishing town in southern Alaska, the ice worm is something of a local mascot. In fact, residents dedicate eight days each February to celebrate the creature, mysteries and all.

The Cordova Ice Worm Festival

February is a bleak time in Cordova, Alaska. It’s dark 16 hours out of every 24. Temperatures hover around freezing. The sky is gray and bloated with clouds. It can sideways rain for weeks on end. And there’s not much to do—most of the town’s 2,500 full-time residents rely on fishing and tourism, both summer industries, for their livelihoods.

Aerial view of Cordova Alaska
Most of Cordova's 2,500 full-time residents rely on fishing and tourism, both summer industries, for their livelihoods. Forest Service Alaska Region, USDA

In the winter of 1961, locals finally got sick of the doldrums.

“Everybody was down on their luck, and the weather was terrible,” says lifelong Cordova resident Kelsey Hayden. “So a group of guys got together over drinks to put something together.” They wanted a festival, and they decided they needed a mascot that was uniquely Cordovan. A salmon or a crab would make sense, given the fishing economy, but this was winter. A few drinks in, they chose the ice worm. To them, Hayden says, it was a symbol of hardiness and resilience. But mostly, it was just fun and different.

That first Cordova Ice Worm Festival was a success, albeit small. Festivities included fishing contests, a dog-catching contest, a ski race, a community parade and fireworks. (Summer fireworks are impossible in Alaska given the nearly 24 hours of daylight.) But the biggest hit was the giant ice worm float, a blue-and-white get-up made of fabric and hoops and designed to fit over the heads of puppeteers like a Chinese dragon. It was 150 feet long, had 37 pairs of legs and immediately captured locals’ imaginations. The float’s debut was perhaps the biggest single moment for ice worm publicity in the organism’s five-million-year history.

The secret lives of ice worms

The reason most people have never heard of ice worms is that they’re difficult to find. They spend most of the day under the ice, hidden from view. Scientists don’t know how deep into the glacier they go. They don’t know how they breed. They’re not even positive what they eat, explains Scott Hotaling, an ecology researcher at Utah State University.

“We think they act a lot like earthworms in a compost bucket,” Hotaling says. “They just move through the substrate taking in whatever is in front of them. So, in this case, they’re taking in mostly snow and meltwater.” Along the way, they pick up algae and bacteria and likely absorb nutrients from those organisms.

That said, ice worms can live for years without food. Hotaling has had ice worms in his refrigerator for more than 18 months and knows colleagues who’ve had their fridge worms for two years or more. Hotaling changes his worms’ ice regularly but feeds them nothing. Despite the long famine, they remain healthy.

Cordova Ice Worm Festival parade
The Cordova Ice Worm Festival is still going on much as it always has. The fireworks are still a staple, as is the ice worm parade float. Emily Mesner

So, without food, how do they survive in Alaska’s extremely cold temperatures?

“They don’t,” Hotaling says. Ice worms actually have a fairly narrow temperature range. Put them in your freezer, and they’ll die of hypothermia. Keep them at room temperature, and their membranes will melt.

The secret to the ice worm’s success is that the inside of a glacier doesn’t get colder than 32 degrees Fahrenheit. Snow and ice are such good insulators that the temperature within a glacier is almost always right around freezing. Whenever an ice worm starts to get chilled, it digs deeper, seeking the warmth of the inner glacier.

“If you put them on the surface of the snow when it’s below freezing, they will immediately burrow into the snow,” Hotaling says. “It’s the fastest you’ll ever see an ice worm move.”

That said, 32 degrees Fahrenheit is still a pretty extreme environment for an ectotherm, or cold-blooded animal that is dependent on external sources of heat. For a bird or mammal with a robust food source and plenty of insulation, it’s not so bad. But for a tiny worm that can’t produce its own body heat, glaciers make an unlikely habitat. Fortunately, ice worms have some highly specialized machinery to help them cope.

The powerhouse of the cell

For years, scientists weren’t quite sure how ice worms managed to produce energy in an environment so bereft of food and heat.

“Most biochemical processes tend to work better when there’s a little warmth,” says Hotaling. He suspects the worms’ dark coloring helps them absorb solar radiation, warming themselves up just enough to kick-start their cellular machinery. Other scientists, like Daniel Shain of Rutgers University, suspect there’s a little more to the story.

close-up of ice worms
Ice worms are the only macroscopic animals adapted to live inside ice. Scott Hotaling

“Energy is a big problem when it gets cold,” Shain says. “If you jump into a reservoir in the middle of the winter, you’ve got like ten minutes before you’re dead. Your energy just gets completely depleted in those temperatures. You just can’t make it fast enough compared to how much you’re using, and that’s the end of the game.”

In most organisms, cold slows the metabolism and brings energy production to a grinding halt. But with ice worms, it’s the opposite. The colder it gets, the more energy they produce.

Like us, ice worms make their energy using mitochondria (“the powerhouse of the cell” as you may remember from your high school biology days). That energy gets stored in a molecule called adenosine triphosphate (ATP). This molecule is produced by mitochondrial ATP synthase, a molecular machine made up of numerous parts.

Across most organisms, ATP synthase looks pretty similar. But in ice worms, one of its key parts, a component called ATP6, is unusually long. Suspiciously long, in fact.

ATP6 regulates the flow of hydrogen ions through ATP synthase. The quicker the ions pass through, the more ATP that gets made. In ice worms, the ATP6 structure is so long that it juts deep into the mitochondria’s inner matrix, reaching far away from the bulk of the ATP synthase machine. This is where things get interesting.

Remember the concept of osmosis from your high school biology class? Particles, including hydrogen ions, tend to flow from areas of high concentration to low concentration. Mitochondria naturally have fewer hydrogen ions in their inner matrix than near their outer edge. The long, jutting piece of ATP6 is able to span that gradient. As a result, ions move across its length from areas of high concentration to low concentration. Basically, it’s like a little conveyor belt for hydrogen ions. The conveyor belt quickly shuffles the ions away from ATP synthase, maintaining the concentration difference that drives ATP production. In ice worms, the colder it gets, the faster this process becomes—ensuring that energy production keeps up, even at 32 degrees Fahrenheit.

Stolen genes

The plot twists don’t stop there. A few years ago, Shain’s colleague at the time, Shirley Lang, took a closer look at that funky, abnormally long ATP6 structure. She did a database search, scanning through known genomes to try to find proteins with similar sequences of amino acids. And she did—in fungi, specifically ice-adapted fungi, a major component of the ice worm’s diet.

Lang’s theory is one of horizontal gene transfer. Basically, she believes that an ancient ice worm was chomping through the snow one day when it swallowed a bit of fungus—and accidentally absorbed some of the fungal genetic material into its own cells.

“Horizontal gene transfer is very common in plants and prokaryotes, such as bacteria,” Lang says. It’s less common in eukaryotes (like worms), but it has been known to happen from time to time. For example, tardigrades—sometimes called “water bears”—pick up genes like this all the time.

In this case, the ice worm was the beneficiary of a very happy accident. The absorbed chunk of mitochondrial DNA was so effective for survival that it rapidly spread throughout the ice worm population. Today, this particular machinery appears to be universal among ice worm species, and ice worms are the only creatures on Earth known to make energy this way.

The melanin mystery

The other big mystery surrounding the ice worm involves its coloring. Though Cordova’s ice worm parade float is white and blue, real ice worms are black. They owe their coloring to abnormally high quantities of melanin, which is not just in their skin but layered deep within their muscles and organs as well.

Some scientists, like Hotaling, believe this much pigment helps them withstand ultraviolet damage. The melanin may also help them absorb solar radiation to keep themselves warm, he suggests. Other researchers believe it must have another purpose. That’s because plenty of cold-adapted animals—from tardigrades to Antarctic insects—are chock full of melanin.

“Melanin has unique electrical properties. It conducts electricity. Right now, there’s a lot of research being done into using it for bioelectrodes and biosensors for biomedical applications,” Lang says. She suspects that Arctic critters like the ice worm use melanin to make energy more efficiently.

Everyone’s favorite worm

Cordova Iceworm Festival mascot
The festival's founders chose an ice worm as the mascot because it was hardy and resilient. But mostly, it was just fun and different. Design Pics Inc/Alamy Stock Photo

Sure, the ice worm may have cutting-edge cellular machinery. It may have electrically conductive skin and muscles. And it may travel from glacier to glacier on the feet of birds. But that’s not why it’s captured the hearts of so many.

“They’re just awesome,” Hotaling says. “They’re high on my list of favorite animals for sure. They live in the places I love. I love those high-mountain, snowy landscapes. To me, ice worms are the embodiment of those places. They’re symbols of what I care most about in the natural world.”

Cordova locals seem to feel the same way. Now, 63 years later, the Cordova Ice Worm Festival is still going on much as it always has. The fireworks are still a staple, as is the float. The modern fest is a full eight days long and includes an oyster-shucking contest, an adult basketball tournament, a cribbage competition and a beauty pageant. The winner of the pageant is crowned that year’s “Miss Ice Worm.”

This year’s festival is currently underway, running from January 27 to February 3. Volunteers dusted off the giant ice worm and built other parade floats. Local dance troupes and bands prepared routines. Hayden, who is on the Ice Worm Festival committee, says most of the town participates, and hundreds of other visitors travel in from neighboring cities.

“The festival is truly special for Cordova. It’s our oldest festival, and it was created by and for the community,” she says. “I think it speaks to the resiliency and tenacity of our residents and highlights the tight-knit community that we really are. We’ve had booms and busts in our history. But for 63 years now, rain or shine, people come out after the holidays to make the festival happen.”

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