Indestructible tardigrades will outlive all

Great news for everyone’s favourite vacuum bag-shaped microanimal – the near-imperishable tardigrade will outlive us all, persisting until the Sun dies in around 5 billion years, according to a new study.

If a big enough asteroid hits Earth, humans will likely perish. Not so for the tardigrade – a hardy, eight-legged creature that lives in in watery environments across Earth, from mountains to the deep sea.

This resilient species can withstand extreme conditions including 150-degree heat, pressure six times what you find in an ocean trench, and up to 30 years without food or water – all of which which will aid their survival.

To assess this resilience, scientists at Oxford and Harvard Universities zeroed in on three kinds of potential astrophysical events: asteroid impacts, gamma ray bursts, and exploding stars in the form of supernovae. Their results are published in Scientific Reports.

They deduced that to kill off tardigrades, an astrophysical event would need to pack enough punch to boil Earth’s oceans. This means a hefty asteroid, a supernova within 0.14 light-years of Earth, or a gamma-ray that burst no more than 40 light-years away.

None of these situations are particularly probable – our closest asteroids and stars aren’t big enough to achieve these outcomes. As a result, the research suggests tardigrades will live through any major astrophysical impact likely to occur on Earth, potentially giving them another 5 billion years of life.

“A lot of previous work has focused on ‘doomsday’ scenarios on Earth – astrophysical events like supernovae that could wipe out the human race,” says co-author David Sloan, a physicist at Oxford University.

“Our study instead considered the hardiest species: the tardigrade.”

Co-author Rafael Alves Batista, also at Oxford, says the incredible resilience of tardigrades is a strong argument for the existence of life on other planets.

“Tardigrades are as close to indestructible as it gets on Earth, but it is possible that there are other resilient species examples elsewhere in the universe. In this context there is a real case for looking for life on Mars and in other areas of the solar system in general. If tardigrades are Earth’s most resilient species, who knows what else is out there?”

Related reading: Tardigrade protein fortifies human cells

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