Move over, tardigrades! Rotifers can live in frost for 24,000 years

Move over, tardigrades! Rotifers are the new contender for the world’s toughest creatures after scientists discover them alive in the Arctic having been frozen for 24,000 YEARS

  • Bdelloid rotifers are so tiny that you’d need a microscope to be able to see them
  • Experts in Russia extracted a sample of the incredible microorganisms in Siberia
  • They can survive ‘seemingly indefinitely’ in suspended animation under the ice 

The bdelloid rotifer – a minuscule microorganism invisible to the naked eye – can live in frost for 24,000 years, a new study reveals. 

Russian experts say the microscopic invertebrate, about 0.008 of an inch in length, can survive ‘seemingly indefinitely’ in suspended animation beneath Siberian permafrost – ground that remains completely frozen. 

Insights from these tiny animals could offer clues as to how better to cryo-preserve the cells, tissues, and organs of other animals, including humans. 

Despite their size, bdelloid rotifers are known for being tough, capable of surviving through drying, freezing, starvation, and low oxygen. 

In this sense, they’re similar to tardigrades – tiny animals that are almost indestructible, and can even survive in outer space.

Bdelloid rotifers are multicellular animals so small you need a microscope to see them. Despite their size, they’re known for being tough, capable of surviving through drying, freezing, starvation and low oxygen


Rotifers are minuscule microorganism invisible to the naked eye without a telescope. 

Rotifers can be found in many freshwater environments and in moist soil, where they inhabit the thin films of water that are formed around soil particles.

Rotifera is divided into three classes – monogononta, bdelloidea and seisonidea. 

The largest group is the monogononta, with about 1,500 species, followed by the bdelloidea, with about 350 species. There are only two known species of seisonidea. 

Source: University of California Museum of Paleontology 

The new study on bdelloid rotifers has been conducted by experts at the Soil Cryology Laboratory, Institute of Physicochemical and Biological Problems in Soil Science, in Pushchino, Russia.

The lab specialises in isolating microscopic organisms from the ancient permafrost in Siberia, using a drilling rig in some of the most remote Arctic locations. 

‘Our report is the hardest proof as of today that multicellular animals could withstand tens of thousands of years in cryptobiosis – the state of almost completely arrested metabolism,’ said study author Stas Malavin.

‘The takeaway is that a multicellular organism can be frozen and stored as such for thousands of years and then return back to life – a dream of many fiction writers.’ 

Rotifers had been reported to survive up to 10 years when frozen, based on earlier evidence.

In the new study, the researchers used radiocarbon-dating to determine that the bdelloid rotifers recovered from permafrost were able to survive 2,400 times this amount. 

Once thawed, the rotifer, which belongs to the genus Adineta, was able to reproduce in a clonal process known as parthenogenesis (reproduction without fertilisation). 

To follow the process of freezing and recovery of the ancient rotifer, the researchers froze and then thawed dozens of rotifers in the lab.

The studies showed the rotifers could withstand the formation of ice crystals that happens during slow freezing. 

It suggests they have some sort of mechanism, as yet unknown, to shield their cells and organs from harm at exceedingly low temperatures. 

‘Of course, the more complex the organism, the trickier it is to preserve it alive frozen and, for mammals, it’s not currently possible,’ said Malavin.

‘Yet, moving from a single-celled organism to an organism with a gut and brain, though microscopic, is a big step forward.’

It’s not yet clear what it takes for a rotifer to survive on ice for even a few years – and how techniques to do so change when this is extended to thousands of years. 

The researchers say they’ll continue exploring Arctic samples in search of other organisms capable of such long-term cryptobiosis, which may help provide answers.

Lateral view of rotifer. Rotifera is divided into three classes – monogononta, bdelloidea and seisonidea. The new research looked at a species in the genus Adineta (pictured) which is part of bdelloidea

Malavin pointed out that not all rotifers have the resilience of bdelloid rotifers. 

Individuals of another class of rotifer – monogonont – aren’t adapted to hazards like including drying, freezing and low oxygen when adults. 

However, in the autumn, monogonont rotifers produce special eggs that are resistant to starvation and low oxygen, and partially to freezing, but not to drying, to survive during the winter, he said.  

The new research paper, published today in the journal Current Biology, follows a wave of recent interest in ultra-resilient microorganisms. 

The most famous are arguably tardigrades, which have proven to be virtually impossible to kill – even when frozen, boiled, crushed or zapped with radiation.

Tardigrades first made national news in April 2019 when they were mistakenly left on the moon’s surface after the Beresheet probe crashed on the lunar surface

Tardigrades are also known as water bears, because of their podgy and slightly adorable appearance. 

They were first discovered by the German zoologist Johann August Ephraim Goeze in 1773, who gave them their affectionate nickname.

On whether tardigrades or rotifers are more resilient, Malavin said it depends on which particular species are in question.  

Both ‘tardigrades’ and ‘rotifers’ are names of two different phylum, each made up of more than 1,000 species.  

‘Generally speaking, all animals adapted to frequent irregular drying and freezing are much more tough than those not adapted,’ he told MailOnline.

‘To figure out who’s the toughest requires quite a lot of study no researcher will ever conduct.’  


Tardigrades, also known as water bears, are said to be the most indestructible animals in the world.

These small, segmented creatures come in many forms – there are more than 900 species of them – and they’re found everywhere in the world, from the highest mountains to the deepest oceans.

Tardigrades, also known as water bears, are said to be the most indestructible animals in the world.

They have eight legs (four pairs) and each leg has four to eight claws that resemble the claws of a bear.

Boil the 1mm creatures, freeze them, dry them, expose them to radiation and they’re so resilient they’ll still be alive 200 years later.

An illustration of a tardigrade (water bear) is pictured 

Water bears can live through temperatures as low as -457 degrees, heat as high as 357 degrees, and 5,700 grays of radiation, when 10-20 grays would kill humans and most other animals.

Tardigrades have been around for 530 million years and outlived the dinosaurs.

The animals can also live for a decade without water and even survive in space.

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