Featured Creature: Tardigrade

What microscopic creature can survive space and bullets, and may offer a way for humans to survive on other planets?

**The Tardigrade (Tardigrada)!**

WGabriel, Goldstein Lab via Wikimedia Commons

Bio4Climate intern Melanie Davis-Kay believes that some of the most fascinating creatures on our planet are the ones that we can’t see with the naked eye. As such, she thought it only fitting that her first Featured Creature focuses on what she finds to be one of the most interesting microorganisms, the tardigrade.

One of the most resilient and impactful creatures on our planet is so small you can literally walk past thousands of them without even knowing it. Also known as “water bears” or “moss piglets,” tardigrades are tiny eight-legged animals about 0.02 inches in length. Compared to other microorganisms, Tardigrades are just darn cute, in large part because of their resemblance to piglets. Their mouths resemble a snout, and their bodies are just as round and chubby as swine. They are also known for their adorable waddle!

Cute as they may be, these little powerhouses are some of the toughest living creatures on our planet. They also have a large impact on the ecosystem and offer significant potential for science and space exploration.

Looking for Fresh Water? Ask a Tardigrade!

Tardigrades thrive wherever moisture collects: mosses, soil, leaf litter, lichens, freshwater streams, and saltwater environments. Tardigrade numbers are staggering, especially in mossy environments, where scientists have estimated that there are around 2 million tardigrades per square meter of moss. More specialized species have adapted to life as parasites inside marine invertebrates like crustaceans and sea scallops. They’ve even been spotted near hot springs and floating among seaweed.

Because they are so lightweight, tardigrades can also travel on the wind, drifting long distances through the air. It’s highly likely that you have encountered multiple tardigrades in your lifetime without ever realizing it. My personal favorite is to imagine blowing on a dandelion, with tens of thousands of tardigrades going along for the ride.

Tiny Bodies, Big Impacts

Tardigrades play a genuine and important role in the health of the environments they inhabit. Because they depend on clean fresh water to survive, they are indicators of healthy ecosystems. A thriving tardigrade population signals a healthy ecosystem, while a concentration of dead tardigrades points strongly to pollution. Scientists use them as biological markers to assess the condition of soil and water, making them one of nature’s most accessible monitoring tools.

Below ground, tardigrades are active participants in keeping soil ecosystems in balance. They feed on harmful bacteria and nematodes that would otherwise degrade soil quality. By controlling the damaging populations, tardigrades help sustain the microbial balance that supports plant growth, nutrient cycling, and the broader food web.

To Cold, Pressure, Radiation, Space…and Beyond!

One of the most notable adaptations of the tardigrade is their environmental tolerance. Scientists have tested every environmental factor on this creature, and they have survived them all. This is because the tardigrade can go into cryptobiosis, otherwise known as a “tun” state. When their water source dries up, tardigrades curl up into a desiccated cyst, where no metabolic activity takes place. The tardigrade’s body is frozen in time until they are rehydrated. The tun state can last for several years, which has led scientists into experimenting what other factors the tardigrades can survive.

Tardigrades can survive extreme temperature, both hot and cold. This can be between a few minutes at 304 °F, to 30 years at −4 °F. They have also survived bullet impacts at speeds up to 3,000 feet per second. When hydrated, the tardigrade can withstand up to 5,000 gamma rays of radiation. That’s a thousand times more than any human or animal can survive. Arguably the tardigrades’ most impressive feat is their survival in space. In the twenty-first century, tardigrades have been sent on 3 different space missions. In 2007, dehydrated tardigrades were launched into low Earth orbit on the FOTON-M3. For 10 days, they were exposed not only to more radiation, but the cold vacuum of space. When they touched back down to Earth and were rehydrated, the tardigrades survived with no lasting injuries.

The BIOPAN which took the tardigrades into space in 2007. Hnapel via Wikimedia Commons

In 2011, tardigrades were sent to space on the STS-134 Space Shuttle Endeavor as part of the “Tardigrades in Space” experiment, otherwise known as TARDIKISS. Through this mission, it was discovered that microgravity and cosmic radiation had no major effects on the tardigrades. In 2019, tardigrades were sent to the moon by the Israeli lunar lander Beresheet. Unfortunately, the lander crashed into the moon. If the impact did not kill the tardigrades already, they could not survive on the moon without liquid water.

Despite all these impressive feats, the tardigrade is not indestructible. Even though the tardigrade can spend a few minutes in extreme heat, they cannot go longer than that without dying. While the vacuum of space did not affect the tardigrades’ egg-laying, the radiation from space did. And even with everything they had survived, if they continued to be harmed with these environmental factors, it would all weaken them until they died.

However, the negative outcomes for environmental tolerance have not stopped scientists from experimenting on the tardigrade. Yet this time, they’re not focused on how the tardigrade can save themselves—it’s on how they can save us.

The Tardigrade Will (Maybe) Cure Us All

Antonio Segura Torres & Vieto Bonilla via Wikimedia Commons

Because of the tardigrades lasting endurance, many scientists are experimenting with the different ways the creature can benefit our health. One of those ways can be through vaccine development. Vaccines must be kept at low temperatures, which can be costly and could lead to other issues. With the longevity of tardigrades in below freezing temperatures, scientists are hoping to use their proteins to self-cool the vaccine. This would allow the vaccine to be stored in room temperature environments.

Another way that the tardigrades might help us, believe it or not, is through sunscreen! If the tardigrade can survive up to 1,000 times more radiation than we can, then shielding us from the sun should be a walk in the park!

With the tardigrades’ ability to survive long periods of drought, scientists have wondered if their properties can be transferred into crops. If the crops can survive long droughts as the tardigrade can, it would be useful as the lasting effects of climate change continue to affect the water cycle. The healing properties can also be useful to humans. The fast-healing proteins of the tardigrade might also be used to stabilize serious injuries and cell death. While the tardigrade has no properties that can cure cancer, they could protect and repair the damaged cells affected by chemotherapy.

With the survival of tardigrades in space, the next question becomes about humans. Could the tardigrades be our stepping stone into populating other planets? With all the other medical possibilities stated, there is no defined answer. Years of research needs to be done before we can definitively say how the tardigrade helped our progress on the medical front.

For a creature that is just .02 inches long, tardigrades have the potential to make big impacts on the future of humanity.

Melanie Davis-Kay is a soon-to-be graduate from Lesley College. She was a former volunteer at The Discovery Room inside the Museum of Science. She lives in Arlington, MA.