Tardigrades, also known among their many fans as ‘water bears’ or ‘moss piglets’, are quite possibly the cutest microscopic creatures on the planet – and off it.
These mini beasts have been sent up for a stint on the International Space Station and scientists have even launched them out into the vacuum of space.
Left for days with no air, water or protection from intense solar radiation, the tardigrades, amazingly, did just fine. Scientists are figuring out what makes these little animals so indestructible.
When the going gets tough, tardigrades enter an extreme form of hibernation, as cryptobiosis, in which they dry out and hit pause on their metabolism.
Then, when conditions improve and water is available, the tardigrades will rehydrate and go about their business as if nothing happened.
In recent years, many pieces of the tardigrade puzzle have been falling into place. We now know, for instance, that a protein known as ‘Dsup’ moulds to their DNA and shields it from radiation, like a molecular suit of armour.
Researchers based at the University of Stuttgart have found evidence supporting the so called ‘Sleeping Beauty’ hypothesis.
The idea is that, in their resting state, tardigrades might not only pause their metabolism, but also their biological clocks.
Water bears that had been periodically frozen lived twice as long, in their waking state, as a control group that never went to sleep.
In their natural habitats, tardigrades may only be active for a few months in total, but they can spread their lives out over many decades, sleeping through inhospitable periods.
A 2024 study focused on a recently discovered species of tardigrade, Hypsibius henanensis, which provided another piece of the puzzle.
The research team found a gene in this species that produces pigments known as betalains, that help neutralise the harmful effects of UV radiation.
They also learned more about a protein that speeds up DNA repair. The next step will be to see if these proteins protect any of the 1,300 known species of tardigrade.
This article is an answer to the question (asked by Madison Halladay, via email) 'What makes tardigrades so indestructible?'
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