Meet The Most Indestructible Organism Ever Discovered

Nature is full of impressively resilient creatures. Take scorpions, for example, which have been around for about 437 million years and have outlasted numerous other species that were wiped out by mass extinction events. Or yaks, who have adapted to mountain environments to the extent their hearts and lungs are large enough to allow them to survive among the thin air at 18,000 feet above sea level. Even camels are remarkable for their ability to tolerate temperatures of up to 120 degrees Fahrenheit (49 degrees Celsius), and survive losing water equivalent to 25% of their entire body weight.

But even these robust beasts pale in comparison to a microscopic animal that is one of the toughest creatures ever to exist. This tiny organism has been on Earth for around 600 million years, meaning it both existed before and outlived dinosaurs. It is so adaptable that it's basically indestructible, even when exposed to extreme heat, extreme cold, radiation, or even space itself. This deceptively strong creature is known as a tardigrade and is remarkable for its ability to essentially suspend all biological activity in order to survive extreme environments.

There are actually quite a few creatures that could survive an apocalypse, but none are quite so hardy as the tardigrade. First discovered in 1773 by German pastor J.A.E. Goeze, these miniscule animals measure less than 1 mm in length, have eight legs with four to six claws on each, and are considered aquatic due to the fact they need a thin layer of water around their bodies. But while they are technically aquatic, these creatures, which earned the nicknames "water bear" and "moss piglet" for their seemingly squishy morphology, have been found everywhere from the ocean to sand dunes.

About 1,300 species of tardigrades are known to exist, and while the nearly indestructible animals may look cute and cuddly under a microscope, they are actually covered in a hard cuticle similar to many insects. Their unique mouth, known as a bucco pharyngeal apparatus, enables tardigrades to suck nutrients from other organisms, and the animals particularly like to live among mosses and lichens.

While the details of the tardigrade's appearance and morphology are interesting, there's no doubt that it's their extreme hardiness which makes the microscopic creature so fascinating. According to the Science Education Resource Center, the animals can survive temperatures as low as -328 degrees Fahrenheit (-200 degrees Celsius) and as high as 304 degrees Fahrenheit (151 degrees Celsius). They can persevere through the freezing and thawing processes, changes in salinity, a complete lack of oxygen or water, and can survive X-ray radiation 1,000 times the lethal human dose. 

Tardigrades can also weather many noxious chemicals, boiling alcohol, the low pressure of a vacuum, and can survive six times the pressure of the deepest part of the oceans. Add to that the fact that these creatures can take ultraviolet radiation and survive the vacuum of space and you've got one sturdy microscopic beast.

One method tardigrades use to survive is encystment, whereby they surround themselves with multiple cuticles to form a capsule, which in turn forms a barrier between the tardigrade and its surrounding environment. But that is just the beginning of the water bear's defenses.

Tardigrades' remarkable hardiness can mostly be attributed to two things. Firstly, the tiny creatures carry a unique protein called Dsup, which is a contraction of the phrase "damage suppressor." While it might sound like some sort of health boost upgrade in a video game, Dsup is a nuclear protein that binds to a section of DNA inside the nucleus called nucleosomes, thereby protecting that DNA from ionizing radiation and the oxidants it produces.

But having fortified DNA is only one part of the story. Arguably the more impressive survival feature of the tardigrade is its ability to enter a state called cryptobiosis, which essentially means the animal halts all biological function and becomes effectively dead for a prolonged period of time, before reactivating when its surroundings become more conducive. In reality, the tardigrade enters a state of hibernation, squeezing all water from its body, suspending its metabolism, retracting its head and legs, and rolling into a ball. Even more remarkable is the fact that tardigrades can stay in this dormant state for more than 30 years.

A study published in Current Biology showed that tardigrades could survive the vacuum of space and that some specimens could even simultaneously withstand exposure to solar radiation. The researchers noted how the results meant that tardigrades were the first animal ever to have been shown to survive such conditions. Interestingly enough, since this study, thousands of tardigrades ended up stranded on the moon after an Israeli spacecraft containing the creatures crash landed there in April of 2019. 

As Science reported, Tardigrades even proved they could be shot out of a gun at high speed and survive. This particular study, inspired by the spaceship crash that would have seen the animals blasted into the surface of the moon, actually packed tardigrades into a nylon bullet and fired them out of a two-stage light gas gun — which uses gunpowder and highly compressed hydrogen to fire projectiles at speeds far beyond that of a regular gun. The study revealed that the creatures could survive impacts up to about 900 meters per second into a target made of sand, and momentary shock pressures of up to 1.14 gigapascals (GPa). While that may sound as if it proves the tardigrade's reputation as nearly indestructible, the researchers did note that, beyond these speeds, the creatures became "mush" — suggesting that those aboard the Israeli spacecraft likely died on impact.

If you needed any more convincing that tardigrades are about as tough as animals come, then how about the University of Oxford and Harvard declaring that the creatures will not only outlive humans, but could even survive the death of our sun?

A study, published in Scientific Reports concluded that tardigrades would likely survive any astrophysical calamities that hit our planet, including the death of the Sun — which would actually be much slower than an explosion. In other words, tardigrades, which have already been in existence for roughly 600 million years, are expected to stick around for at least another 6 billion — and likely 10 billion — years.

In 2006, the Astronomer Royal, Martin Rees, published one of his talks under the title "Dark Material," in which he says, "Any creatures witnessing the Sun's demise 6 billion years hence won't be human — they'll be as different from us as we are from bacteria." It's a stultifying thought to envision what kind of beings could watch the Sun die, but perhaps even more stultifying is the thought that, by that point, while we will be long gone, the tardigrade will remain just as it is today.