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Tardigrades belong to an elite category of animals known as extremophiles, or critters that can survive environments that most others can't. For instance, tardigrades can go up to 30 years without food or water.
Research shows that tardigrades can be killed by exposure to hot water for an extended period of time. One study showed that one hour of exposure to water at 82.7 °C (180.9 °F) can kill a tardigrade in its “tun” state, where it goes into suspended animation and becomes hard to destroy.
Tardigrade Lifespan
In terms of their natural lifespan, some live a few months, while others can live for up to 2 years. But they can also go into a dormant state which stretches their lifespan even further. In this state, they can go more than 30 years without any food or water.
At least two species of tardigrade also produce another protein found in no other animal on Earth. This protein, dubbed Dsup, short for “damage suppressor,” binds to DNA and may physically shield it from reactive forms of oxygen.
Tardigrades are practically unkillable. The microscopic creatures, commonly known as "water bears," can tolerate stress that would end most other organisms. The vacuum of space? No problem for the moss piglets.
Tardigrades aren't completely bulletproof, after all.
What kills tardigrades? Research shows that tardigrades can be killed by exposure to hot water for an extended period of time. One study showed that one hour of exposure to water at 82.7 °C (180.9 °F) can kill a tardigrade in its “tun” state, where it goes into suspended animation and becomes hard to destroy.
Tardigrades are nearly translucent and they average about half a millimeter (500 micrometers) in length, about the size of the period at the end of this sentence. In the right light you can actually see them with the naked eye.
The microscopic water bears that can survive desiccation, extreme cold, and even trips to the Moon have a key weakness: heat. A recent study tested the survivability of a tardigrade species at elevated temperatures over an extended period.
You can boil them, bake them, deep-freeze them, crush them, dehydrate them, or even blast them into space. It doesn't matter—tardigrades can survive practically anything. These eight-legged aquatic animals may be small, but they're nearly indestructible.
Are tardigrades dangerous? No, at least not to humans. Other micro-organisms in their environment should be on notice though; those claws aren't for show. While most tardigrades are herbivorous, not all of them are, and they will eat you if you are smaller than they are and you are within reach of their claws.
Tardigrades are nature's pioneers, colonizing new, potentially harsh environments, providing food for larger creatures that follow. Scientists say, for instance, that tardigrades may have been among the first animals to leave the ocean and settle on dry land. Tardigrades pose no threat to humans.
Tardigrades, the Toughest Creatures on Earth, Have an Achilles' Heel—Global Warming. Tardigrades are one of the toughest species on the planet. They can survive being boiled and frozen, and go a decade without water. They are also the only known creatures to have survived the vacuum of space.
Meet the Tardigrade – The Toughest Animal on Earth.
Tardigrades are among the most resilient animals known, with individual species able to survive extreme conditions – such as exposure to extreme temperatures, extreme pressures (both high and low), air deprivation, radiation, dehydration, and starvation – that would quickly kill most other known forms of life.
Our data reveal that the tardigrade nervous system develops in an anterior-to-posterior gradient, beginning with the neural structures of the head. The brain develops as a dorsal, bilaterally symmetric structure and contains a single developing central neuropil.
They Can Go Decades Without Food or Water
Perhaps the most famous thing about tardigrades is their uncanny durability. Tardigrades are not immortal, but they have a powerful adaptation that allows them to survive for decades in extreme conditions: cryptobiosis.
1) First things first: Tardigrades are uncannily cute
Just look at one and you'll see why. Tardigrades — which grow up to a millimeter in length — swim with four sets of stubby legs that appear much too small for their bodies. At the end of each leg is a set of stubby little claws.
It is virtually impossible kill a tardigrade. You can freeze it, boil it, crush it, zap it with radiation, and deprive it of food and water—for years! —and it will wiggle back to life.
Tardigrades may be microscopic, but they contain mammoth adaptability for surviving extremes, including deadly radiation.
There are more than 900 known tardigrade species, the largest being Echiniscoides sigismundi, a marine dweller from Eurasian waters that reaches 1.5 mm (0.05 in) as an adult.
The tardigrades were in “tun” form, a dormant state where they shrivel up into a ball, expel most of the water in their bodies, and lower their metabolism via cryptobiosis until they enter an environment better suited for sustaining life. They can exist like this for decades.
But they lack frills like a heart, lungs or veins because their body cavity is what's called "open hemocoel," which means that gas and nutrition can move in, out and around efficiently without complex systems [source: Miller].
They also have simple eyes that notice if it's light or dark out, but they can't see color. Just like us, they have guts that hold and digest food, muscles for moving, and brains for thinking. Unlike us, they don't have lungs, and instead soak up oxygen straight from water.