Tardigrades are the toughest animals on earth. What would it take to kill them all? (2024)

Eventually there will be tardigrades.

If a catastrophe wipes out most life on the planet – including humans – tardigrades are likely to survive. Thisstrangely cute microscopic animalsare among the strongest creatures on earth.

Some can withstand the shock of boiling water and temperatures approaching absolute zero. Others have survived the crushing pressure of the deep ocean or are left without waterdecades. Tardigrades do have thatsurvivedin the vacuum of space. In 2014, Japanese researchersthaweda group of tardigrades that had been frozen for 30 years. What did they do after they woke up? on? The reproduction speech.

But what would it take to... kill them all? (Laughs maniacally.)

What would it take to end all life on Earth?

That's roughly the question a group of physicists asked in a new paperNatural science reportslog.

The purpose of the article is not to pick tardigrades. It's more of a thought experiment.

“Much attention has been paid in the literature to the effects of astrophysical events on human lives and on land,” write the authors, physicists from Oxford and Harvard. “But little has been discussed about the resilience of life itself.”

This question is important because if a mass extinction were to occur, it would be nice to know if life could grow, develop, and flourish again. The asteroid impact that killed the dinosaurs 66 million years ago also occurred80 percent of the other species on Earth. But some small mammals survived. And that is why we are here today.

Tardigrades are a good benchmark for this question. If the extremely tough tardigrades disappear, the Earth would, in the words of the scientists, be "sterilized" of all life.

Why tardigrades are so damn strong

It's important to note: tardigrades are basically indestructible only when they achieve a special state called cryptobiosis.

In harsh conditions, the animals stick their paws in and remove all moisture from the body. In this state they are called tunas.

Like tuna, tardigrades produce and excrete glycerol (antifreeze).trehalose, a simple sugar with remarkable preservative properties. “Trehalose is considered a cocoon that encloses the biomolecule in a glassy matrix, like amber-encased insects,”explainsan article from 2009 iProtein science. When the trehalose crystallizes, so will the tardigradeis becomingmummified in an armor of glass. Just like a tuna, the tardigradedecreasesits metabolism by 99.99 percent while it waits for a more suitable environment.

Different species of tardigrades have different adaptations to a wide range of environmental threats. They do that in warm conditionsEditionheat shock proteins, which prevent other proteins from folding. Some tardigrades may formbubbling cystsaround their body. Like puffer coats, the cysts allow them to survive in harsh climates.

(If tardigrades aren't in tuna shape, "it's very easy to kill them," says one biologistonce assured me.)

Three scenarios that could wipe out tardigrades

So what would it take? The researchers made some assumptions about tardigrades' upper limits for exposure to heat and radiation and examined three scenarios.

1. A nearby star goes supernova, sending deadly radiation to Earth
2. A gamma ray of unknown origin is corrupting the Earth
3. Asteroid impact

Let's start from the top.

In the case of 1 and 2, all hell would break loose on earth. The radiation would destroy the ozone layer, incinerate all life on Earth and destroy our oxygen-rich atmosphere. But in these scenarios it's the tardigradescould bestill survive. “Even complete loss of the atmosphere would have no effect on species living on the ocean floor,” the study authors note.

To really kill all the tardigrades – and all life on the planet – you would have to evaporate the oceans. Which would take an incredible amount of energy.

How many?

560,000,000,000,000,000,000,000,000 joules of energy, the study authors calculate. A joule is a measure of energy that corresponds to the effort required to create one watt of power in one second. 560 septillion of that is “about a million years of total human energy productioncurrent rates", From authorsRemarkin the conversation.

Fortunately, there is no star within very close distance that could produce such energy.

Gamma ray bursts are much more mysterious.

We've only seen them in other galaxies, and they are some of the most energetic events ever observed in the universe. Scientists aren't sure how or why they form. But they could absolutely destroy all life on Earth.

Fortunately, this scenario is unlikely. The source of a gamma-ray burst must be “within about 42 light-years,” the authors saidto write.The chance of this happening is astronomically small. Again, we have never seen a gamma-ray burst in our own galaxy. So it's unlikely that one will show up in our area.

Indeed, there are few planets in the Milky Way "that would ever be sterilized by a gamma-ray burst."

Relief!

It Leavesasteroids. Could an asteroid large enough produce the energy needed to end all life on the planet?

In!

The physicists estimate that it would take an asteroid with a mass of 1.7 quintillion kilograms or more to burn up the oceans. There are only 19 in the solar system. No one is on a collision course with the Earth. The authors also suggest that if dwarf planet Pluto collides with Earth, that would be enough. And then we would finally get rid of the little stupid rascals (and absolutely everything else).

A few notes

Tsujimoto et al. 2016 Cryobiologie (foto van Megumu Tsujimoto/NIPR)

I'm the Washington Postpoints out, there are some important caveats to this article.

The big one is that researchers lump all tardigrades together in their analysis. There are thousands of species of tardigrades – and they all have slightly different adaptations that help them survive. But no one species has all the defense mechanisms of the others.

Those who live in the deep, deep ocean may not be able to withstand as much heat, radiation or other trauma as their land-based counterparts. So this is a bit of a rough sketch. Tardigrades may be a little easier to kill than what is suggested here.

But despite all the talk of death and destruction, the study's authors come to an optimistic conclusion: 'We don't fully understand the mechanisms by which life began, but once it exists on an Earth-like planet, the complete elimination of all life will occur . other than through the evolution of the host star) is a very unlikely event."