Imagine a creature so small it can fit between the grains of sand on a beach with space to spare, yet so resilient that it can survive the inhospitable vacuum of space. If you can’t, that’s alright because we already have one on Earth—the tardigrade.
Tardigrades, informally known as water bears or moss piglets, are diminutive—ranging from 0.3 to 0.5 mm in length—but possess almost supernatural abilities that make them nature’s ultimate survivalists. These creatures thrive in environments where most life forms would perish, from the deepest ocean trenches and the highest mountain peaks to the frozen expanse of Antarctica.
Thanks to the extraordinary adaptations they’ve developed over millions of years of evolution—including resistance to radiation, extreme temperatures and crushing pressures, as well as an ability to enter a state of suspended animation—here are some of the most incredible facts we know about tardigrades.
1. Tardigrades, One Of Nature’s Most Resilient Creatures, Survive Extreme Radiation
The effects of radiation on humans are well-documented—it shreds DNA and can cause fatal mutations. However, tardigrades can endure doses lethal to almost every other life form on the planet, according to a September 2016 article published in Nature Communications.
Research has shown that water bears can survive exposure to gamma radiation at doses as high as 5,000 Gy (Gray) and, in some cases, even up to 6,200 Gy. To put that into perspective, a dose of 10 Gy is enough to obliterate a human.
We know today, thanks to science, that these organisms have developed a unique set of proteins called “Dsup” (Damage suppressor proteins) that protect their DNA from radiation-induced damage. These proteins act like an invisible shield, absorbing energy from the radiation and preventing it from causing harmful mutations to the tardigrade’s genetic code.
2. Tardigrades and Cryptobiosis—Their ‘Tun State’ Makes Them Nearly Immortal
Tardigrades can cheat death by entering a state known as “cryptobiosis”—a complete shutdown of their metabolic processes. When faced with extreme environmental conditions such as desiccation, sub-zero temperatures or a lack of oxygen, they dehydrate and curl into a tiny ball called a “tun,” becoming almost completely inert and showing no signs of life, according to a March 2017 article published in Molecular Cell.
In this state, tardigrades can survive for years, even decades, until conditions improve. This process is enabled by the production of “trehalose”—a sugar that protects their cells from damage during dehydration—and the formation of vitrified proteins that stabilize their cellular structures.
Scientific research shows that tardigrades, when in a tun state, can survive temperatures from just above absolute zero (-459.67°F or -272°C) to over 302°F. In fact, they’ve been revived after being frozen for 30 years, a testament to their unmatched resilience.
Once the environment becomes hospitable again—say, when water returns to an arid habitat—they rehydrate, restart their metabolic processes and spring back to life.
3. The ‘Tardigrades In Space’ Project Proved That They Can Survive The Least Hospitable Environment—Outer Space
As far as habitable environments go, space ranks dead last. It’s as hostile as they come with no atmosphere, extreme temperatures and deadly cosmic radiation. Yet, in 2007, tardigrades became the first animal to survive the vacuum of space.
These incredible organisms were exposed to the harsh conditions of space for ten days as a part of the European Space Agency’s TARDIS (Tardigrades in Space) experiment—and they lived to tell the tale, according to a September 2008 article published in Current Biology.
During the experiment, they were subjected to not just the vacuum of space and cosmic rays, but also unfiltered solar radiation; remarkably, not only did they survive, but some even managed to reproduce after returning to Earth. It’s a feat of endurance that attests to their prodigious ability to repair DNA damage and their efficient antioxidant systems that neutralize the harmful effects of radiation.
A creature that has mastered the art of survival against all odds, the tardigrade exemplifies the wonders of evolution.
Its successful survival in space has had profound implications for astrobiology and the study of life beyond Earth, raising questions about the potential for life to exist in similarly extreme environments elsewhere in the universe.
Tardigrades inspire us to think beyond the boundaries of what we thought life—and nature itself—is capable of. Curious about your place in the natural world? Take this 14-question test and discover where you fit: Connectedness To Nature Scale
