Facts About the Tardigrade

10 Fascinating Facts About the Tardigrade

Tardigrades, often hailed as the toughest creatures on our planet, possess an extraordinary ability to thrive in diverse environments and endure extreme hardships that would spell doom for most life forms. Some tardigrades can bravely endure conditions far beyond anything Earth has to offer, making them nature’s ultimate survivors.

These microorganisms are not only resilient but also incredibly charming, earning them affectionate nicknames such as “water bear” and “moss piglet.” Their compact, rotund appearance adds to their peculiar appeal.

Given their ubiquitous presence and remarkable resilience, it’s worth taking a closer look at these tiny marvels. By delving into the fascinating world of tardigrades, we can gain a better understanding of the hidden ecosystems that surround us. To shed more light on these enigmatic creatures, let’s explore some intriguing tidbits you might not be familiar with.

Microscopic Marvels That Push the Limits: 

Tardigrades exist on the verge of visibility to the human eye. These tiny creatures measure approximately 0.5 mm (0.02 inches) in length, and even the largest among them rarely exceed 2 mm (0.07 inches). While some of the more substantial tardigrades might just be visible without assistance, their translucent nature means that a clear, detailed view typically requires the aid of a low-power microscope.

A Unique Phylum All Their Own: 

Tardigrades occupy a distinctive position in the tree of life, representing an entire phylum, which is a taxonomic rank just below the kingdom. When we think of phyla in the animal kingdom, we often envision vast categories like arthropods (encompassing insects, arachnids, and crustaceans) or vertebrates (comprising animals with backbones).

Tardigrades, however, form their exclusive phylum. Their evolutionary lineage extends back at least 500 million years, potentially sharing a common ancestor with arthropods. Today, scientists have identified more than 1,000 tardigrade species, spanning various habitats from marine environments to freshwater ecosystems and terrestrial realms. These hardy microorganisms have truly carved out a remarkable niche within the web of life.

Creatures with a Head-to-Toe Twist:

 In a rather peculiar evolutionary twist, tardigrades took a unique path in their development. At some early point in their lineage, they underwent significant genetic changes that resulted in a distinctive body structure. Notably, they lost numerous genes responsible for shaping the typical head-to-tail body form found in most animals during their development.

These genetic alterations led to a striking transformation: tardigrades now possess a body primarily composed of head segments. In essence, their entire body structure can be likened to the head region of arthropods. This unusual adaptation sets them apart as organisms with a body plan that differs significantly from the typical animal blueprint, as highlighted in a 2016 study published in Cell Biology. It’s a testament to the diverse and innovative ways life has evolved on our planet.

Masters of Extended Survival:

One of the most astonishing features of tardigrades is their remarkable resilience. While not immortal, these tiny creatures possess an extraordinary adaptation that enables them to endure harsh conditions for extended periods—cryptobiosis.

When faced with environmental stress, tardigrades undergo a dramatic transformation. They enter a state of suspended animation known as cryptobiosis, effectively curling up into what appears to be a death-like condition called a “tun.” During this state, their metabolism grinds to a near halt, operating at only 0.01% of its normal rate, and their water content plummets to less than 1%.

What makes this survival strategy truly incredible is the way tardigrades safeguard their cellular machinery. They replace the water inside their cells with a protective sugar called trehalose. This sugar acts as a preservative, preserving the integrity of the cellular components until water becomes available again.

Tardigrades exhibit different types of tun states tailored to different challenges. For instance, anhydrobiosis allows them to endure desiccation, while cryobiosis shields them from extreme cold. In these cryptobiotic states, tardigrades can endure lengthy periods without access to food or water. They remain in suspended animation until rehydrated, at which point they can return to their normal, active state.

This astounding adaptation has enabled tardigrades to defy the passage of time. Some tardigrades have been reanimated from their tun state after lying dormant for an astonishing 30 years. Outside of their cryptobiotic periods, tardigrades typically live for up to two and a half years, further highlighting their incredible capacity to endure and adapt.

Thriving in the Face of Extreme Pressure:

Tardigrades display an astonishing ability to thrive under immense pressure, even while in their cryptobiotic tun state. Some tardigrades can withstand pressures as high as 600 megapascals (MPa), which is equivalent to nearly 6,000 times the atmospheric pressure found at sea level on Earth. To put this into perspective, it’s about six times greater than the pressure experienced in the deepest ocean trenches on our planet.

What’s particularly remarkable is that even at half this pressure, around 300 MPa, most multicellular life forms and bacteria would not survive. Tardigrades, however, have evolved to endure and adapt to these extreme conditions, further cementing their reputation as nature’s ultimate survivors. Their uncanny ability to thrive in such high-pressure environments underscores the unique and resilient nature of these microscopic wonders.

Pioneers in Space Survival:

Tardigrades earned a significant place in space exploration history when two species embarked on the FOTON-M3 mission in 2007. This mission marked a groundbreaking moment as these tiny creatures became the first animals known to endure direct exposure to the harsh conditions of outer space.

During the 12-day mission, both active and desiccated tardigrades were subjected to the unforgiving environment of space, with some of them exposed to the vacuum of space, radiation, or a combination of both. Astonishingly, the vacuum of space posed no insurmountable challenge for either tardigrade species, and the absence of gravity had only a minor impact on them. In fact, some tardigrades on this mission even defied the odds by laying eggs.However, it’s important to note that tardigrades are not impervious to the rigors of space. The combined effects of vacuum and intense UV radiation did take a toll on these hardy organisms.

However, it’s important to note that tardigrades are not impervious to the rigors of space. The combined effects of vacuum and intense UV radiation did take a toll on these hardy organisms.

Subsequent experiments in space, including a visit to the International Space Station in 2011, reinforced the incredible tolerance of tardigrades to the space environment. Furthermore, in 2019, when the Beresheet probe crash-landed on the moon, a capsule containing tardigrades in a cryptobiotic tun state was part of the payload. While the fate of these lunar tardigrades remains uncertain, it’s important to remember that even if they survived the impact, they cannot reanimate without the presence of liquid water—a testament to the exceptional adaptability of these microcosmic survivors.

Radiation-Resistant Pioneers:

Tardigrades have captured the attention of scientists for their extraordinary resistance to radiation. Studies have revealed that these microscopic creatures can endure levels of radiation roughly 1,000 times higher than what a human can withstand.

Remarkably, tardigrades demonstrate their resilience against the harmful effects of radiation in both active (hydrated) and tun (desiccated) states. This aspect has raised some eyebrows among researchers, as the indirect effects of ionizing radiation are typically expected to be more pronounced in the presence of water. However, it’s worth noting that being in a tun state appears to offer even greater protection against radiation.

Not only do tardigrades survive massive doses of irradiation, but they also go on to produce healthy offspring after being exposed to radiation. This remarkable ability is attributed to their capacity to prevent the accumulation of DNA damage and efficiently repair any damage that does occur. However, it’s essential to understand that even tardigrades have their limits when it comes to radiation exposure, as demonstrated in certain space experiments. Nonetheless, their resistance to radiation remains a fascinating area of study and adds another layer to their reputation as nature’s resilient survivors.

Temperature Tolerant Extremophiles:

Tardigrades showcase an impressive adaptability to temperature extremes. Their resilience spans the entire spectrum, from bone-chilling cold to scorching heat.

Cold-Weather Champions: Some tardigrade species, like the polar tardigrades, have displayed an astonishing ability to endure frigid conditions. These microscopic marvels have survived temperatures plummeting as low as minus 196 degrees Celsius (minus 320 degrees Fahrenheit). Research even suggests that certain tardigrades might brave temperatures as chilling as minus 272 degrees Celsius (minus 458 degrees Fahrenheit), just one degree above absolute zero—a temperature range that defies most life forms.

Heat Survivors: On the opposite end of the spectrum, more heat-tolerant tardigrade species have showcased their adaptability. These exceptional creatures can withstand temperatures soaring as high as 151 degrees Celsius (300 degrees Fahrenheit), marking them as true heat-resistant champions.

Discovering Tardigrades in Your Own Backyard:

One of the most intriguing aspects of tardigrades is their astonishing adaptability to diverse environments. These hardy microorganisms have been uncovered in some of the most extreme places on Earth, ranging from scorching hot springs to the frigid peaks of the Himalayas, and even beneath layers of solid ice. They’ve left their microscopic footprints in tropical rainforests, mud volcanoes, and the depths of lakes and oceans. However, tardigrades aren’t limited to these exotic locales—they’re surprisingly abundant in more commonplace settings as well.

In fact, you might be able to find tardigrades in your own neighborhood. They thrive in a variety of environments, including creeks, meadows, moss patches, leaf litter, stone walls, roof tiles, and even parking lots.

If you’re eager to embark on your own tardigrade hunt, all you need is access to a microscope and a few simple tools. Here’s a basic guide for amateur tardigrade seekers:

  • Collect a small clump of moss or lichen from your chosen location.
  • Place the moss or lichen in a shallow dish and allow it to soak in water overnight.
  • After soaking, remove the excess water, and then gently shake or squeeze the soaked clump to release the water into a Petri dish or a similar transparent container.
  • Using a stereo microscope at low magnification—around 15x to 30x—examine the water in the container.

Earth’s Enduring Inhabitants:

Tardigrades, with their astonishing resilience and remarkable adaptability, have earned a reputation as survivors par excellence. Their lineage dates back at least half a billion years, and they have persevered through the challenges posed by at least five mass extinctions in Earth’s history. When we consider their ability to withstand extreme temperatures, pressures, radiation, desiccation, and even prolonged periods without sustenance, it becomes apparent that they are exceptionally well-equipped to outlast many potential global disasters.

This notion is not just a matter of speculation; scientists have reached a similar conclusion. A study published in Scientific Reports in 2017 examined the risks associated with various catastrophic events that could hypothetically wipe out all life on Earth. These events included asteroid impacts, supernovae, and gamma-ray bursts, which have been implicated in past mass extinctions. Surprisingly, the study found that while human life might be somewhat vulnerable to nearby cataclysmic events, the resilience of Ecdysozoa, the group to which tardigrades belong, such as tardigrades themselves, makes the scenario of global sterilization highly improbable.

In essence, tardigrades stand as testament to the tenacity of life on our planet, suggesting that even in the face of catastrophic events, they are more likely to endure than we are. These microscopic wonders remind us of the remarkable adaptability and enduring nature of Earth’s resilient inhabitants.


Ques. What is a tardigrade? 

Ans: A tardigrade, also known as a “water bear” or “moss piglet,” is a microscopic, water-dwelling organism known for its resilience and adaptability.

Ques. How small are tardigrades? 

Ans: Tardigrades are typically less than 1mm in length, making them almost invisible to the naked eye.

Ques. Where are tardigrades found? 

Ans: Tardigrades inhabit a wide range of environments, from hot springs to the deep sea, and even the frigid peaks of the Himalayas. They can also be found in more common places like moss, leaf litter, and soil.

Ques. What makes tardigrades so resilient? 

Ans: Tardigrades are incredibly resilient due to their ability to enter a cryptobiotic state, suspending their metabolism and surviving extreme conditions like desiccation (drying out), radiation, and extreme temperatures.

Ques. How do tardigrades survive in space? 

Ans: Tardigrades can survive in space due to their ability to endure the vacuum, radiation, and lack of gravity. They’ve been on space missions and even visited the moon on the Beresheet probe.

Ques. Can tardigrades withstand radiation? 

Ans: Yes, tardigrades can survive high levels of radiation. They are known to endure approximately 1,000 times more radiation than humans.


These ten fascinating facts about tardigrades provide a glimpse into the extraordinary resilience and adaptability that make them nature’s ultimate survivors. Whether they’re braving the vacuum of space, resisting the effects of radiation, or thriving in the harshest environments, tardigrades continue to astonish scientists and spark our curiosity about the incredible diversity of life on our planet.

In a world where life has conquered nearly every corner of the Earth, tardigrades stand as a testament to the enduring spirit of life itself. Their tenacity reminds us that even in the face of extreme challenges, there is beauty, resilience, and the unrelenting drive to persist. The tardigrade’s story is a testament to the wonders of the natural world, where the tiniest of creatures can captivate our imagination and teach us valuable lessons about the boundless possibilities of life.

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