What are Tardigrades?

So-called water bears are the toughest animals on Earth - and now scientists suspect they are alive on the Moon

Tardigrade
An adult tardigrade
(Image credit: Goldstein Lab/Flickr)

Tardigrades - also known as water bears - have long been considered the toughest animals on Earth. But now they may hold the title of toughest animal not on Earth, thanks to an accident in space.

When an Israeli spacecraft crash-landed on the moon in April, the mission was deemed a failure. But now the Arch Mission Foundation, the organisation behind the rocket launch, has said it may have left more than mere wreckage behind.

The Beresheet spacecraft was carrying a cargo of tardigrades which had been dehydrated, placed in suspended animation and then encased in artificial amber, reports the BBC.

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That means that “the chances of survival for the tardigrades... are extremely high,” according to mission boss Nova Spivack.

What are tardigrades?

Tardigrades are tiny creatures that are less then a millimetre long and can survive being dehydrated for decades. When dried out, says the BBC, tardigrades “retract their heads and their eight legs, shrivel into a tiny ball, and enter a deep state of suspended animation that closely resembles death”.

But when water is reintroduced, they come back to life, feeding and reproducing as normal.

This is a key reason they are considered among the hardiest animals on Earth, and were selected by the Arch Mission Foundation to go on a journey into space.

According to The Guardian, it would not be the first time water bears have survived harsh conditions, having previously been detected “on mountain tops, in scorching deserts, and lurking in subglacial lakes in Antarctica”.

Lukasz Kaczmarek, a tardigrade expert and astrobiologist at the Adam Mickiewicz University in Poznan, Poland, told the Guardian that the animals could well have survived crash-landing on the Moon.

“Tardigrades can survive pressures that are comparable to those created when asteroids strike Earth, so a small crash like this is nothing to them,” he said. The animals could potentially survive on the Moon for years, he added.

Unfortunately, it’s unlikely that the water bears are currently setting up home on the lunar surface. Without being reintroduced to water, scientists say they will remain in a dormant state.

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