How Cryptobiosis Makes Tardigrades Almost Indestructible

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Living organisms need an energy source, water, and a reasonably stable environment in order to survive. Most lifeforms are very particular about where they live and have limited ranges, but a few can survive just about anywhere. Tardigrades are one such creature, as you discover in the above video. They can endure boiling water, freezing cold, and even the vacuum of space by employing some very special survival strategies. Watch the video, and then we will find out more about these incredible creatures and their mind-blowing adaptions.

What Are Tardigrades?

Tardigrades are affectionately known as water bears or moss piglets and are tiny invertebrates measuring a maximum of 0.05 inches in length. Viewed through a microscope, they look a little like a transparent eight-legged panda or hippo as you can see in the above video. We know of at least 1,000 different species alive on the Earth right now.

Any habitat with water is a potential home for tardigrades. They can be found in oceans, lakes, rivers, and streams. Even the thin water films coating mosses and lichens are sufficient for them and some can even live in sand dunes. They mainly eat the cell fluids of plants, algae, and fungi, which they suck out with their needle-like mouthparts.

Extreme Survivorship

These tiny creatures are virtually indestructible. They have been known to survive in temperatures as low as -328°F and as high as 304°F as well as in toxic chemicals, radiation, boiling alcohol, and both low and high pressures.

They can survive conditions that would wipe out most other life forms, and they’re found in the most extreme environments — from the highest mountains to the deepest oceans.

Cryptobiosis: The Tardigrade Survival Strategy

As the above video explains, tardigrades use a mechanism called cryptobiosis to help them survive extreme environmental conditions. During cryptobiosis, their metabolism slows down, and the normal chemical reactions that usually take place within cells to produce energy are drastically reduced.

Tardigrades are able to use at least five different responses to various types of environmental stress. They are all grouped under the general name of cryptobiosis.

Different Cryptobiotic Mechanisms

The exact mechanism used to achieve cryptobiosis varies according to the environmental challenges faced at the time. During anhydrobiosis (lack of water) they curl in their legs and head to form a little ball called a tun. This minimizes their surface area. Inside, they are reduced to an almost powdered form as a sugar called trehalose replaces water in their cells. They can stay like this for many years, yet once they are back in water it takes just hours for them to revive.

Their response to low temperatures is called cryobiosis during which they also form tuns. They also produce a special protein that disrupts the ice crystal formation, therefore protecting their cells. When exposed to a salty environment (osmobiosis), a tun is formed while the tardigrade also uses advanced osmoregulation to maintain fluid flow out of their cells.

Finally, tardigrades are able to form a cyst inside a cuticle to withstand environmental stress and are very adept at repairing DNA damage caused by radiation and chemicals.

Destroying Tardigrades Is Possible

Despite all of these impressive abilities, tardigrades are not indestructible. They can only survive extreme environments when they enter cryptobiosis. The rest of the time they are quite easy to kill. Also, even in a tun state they do not cope well in very hot water for longer periods — there is an upper limit of what they can cope with. Nevertheless, their survival capabilities are among the most impressive currently known to science. We have a lot to learn from these tiny creatures.