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

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The bdelloid rotifer — a tiny microorganism invisible to the naked eye — can be frozen for 24,000 years, a new study reveals.

Russian experts say the microscopic invertebrates, about 0.008 inches long, can survive “seemingly indefinitely” in suspended animation beneath the Siberian permafrost — soil that remains completely frozen.

Insights from these small animals could provide clues as to how to better cryopreserve the cells, tissues and organs of other animals, including humans.

Despite their size, bdelloid rotifers are known for being tough, able to survive through drying, freezing, starvation and low oxygen.

In this sense, they resemble tardigrades – small animals that are almost indestructible and can even survive in space.

Bdelloid rotifers are multicellular animals that are so small that you need a microscope to see them.  Despite their size, they are known for being tough, able to survive through dehydration, frostbite, starvation and low oxygen

Bdelloid rotifers are multicellular animals that are so small that you need a microscope to see them. Despite their size, they are known for being tough, able to survive through dehydration, frostbite, starvation and low oxygen

WHAT ARE ROTIFERS?

Rotifers are tiny microorganisms that are 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 water films that form 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. Only two species of seisonidea are known.

Source: University of California Museum of Paleontology

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

The lab specializes in isolating microscopic organisms from the ancient permafrost in Siberia, using an oil rig in some of the most remote Arctic locations.

“Our report is the most difficult evidence to date that multicellular animals could withstand tens of thousands of years in cryptobiosis – the state of almost completely stopped metabolism,” said study author Stas Malavin.

“The bottom line is that a multicellular organism as such can be frozen and stored for thousands of years and then come back to life – a dream of many fiction writers.”

Based on previous evidence, rotifers have been reported to survive for up to 10 years when frozen.

In the new study, the researchers used radiocarbon dating to determine that the bdelloid rotifers recovered from permafrost could 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 fertilization).

To monitor the process of freezing and restoring the ancient rotifer, the researchers frozen and then thawed dozens of rotifers in the lab.

The studies showed that the rotifers are resistant to the formation of ice crystals that occurs during slow freezing.

It suggests that they have some kind of mechanism, hitherto unknown, to protect their cells and organs from damage at extremely low temperatures.

“Of course, the more complex the organism, the more difficult it is to keep it frozen alive, and that’s not possible for mammals at the moment,” Malavin says.

‘Yet the transition from a single-celled organism to an organism with guts and brains, although microscopic, is a big step forward.’

It’s not yet clear what it takes for a rotifer to survive even a few years on ice — and how the techniques for doing so will change if this is extended to thousands of years.

The researchers say they will continue to explore Arctic samples in search of other organisms capable of such long-term cryptobiosis, which could help provide answers.

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

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

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

Individuals of another class of rotifers – monogonont – are not adapted to dangers such as drying, freezing and low oxygen in adults.

In the fall, however, monogonal rotifers produce special eggs that can withstand starvation and low oxygen, and partially freeze, but not dry, to survive 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.

Arguably the most famous are tardigrades, which have been 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 accidentally left on the lunar surface after the Beresheet probe crashed on the lunar surface

Tardigrades are also known as water bears, due to their plump and somewhat cute appearance.

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

Whether tardigrades or rotifers are more resilient, Malavin said, depends on which specific species is involved.

Both ‘tardigrades’ and ‘rotifers’ are names of two different tribes, each consisting of more than 1,000 species.

“In general, all animals that are adapted to frequent irregular drying and freezing are much tougher than animals that are not adapted,” he told MailOnline.

‘To find out who is the toughest, it takes a lot of research that no researcher will ever do.’

WHAT ARE TARDIGRADES?

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

These tiny, segmented creatures come in many forms—there are over 900 species—and they can be found all over the world, from the tallest mountains to the deepest oceans.

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

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 a bear’s claws.

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

An illustration of a tardigrade (water bear) is shown

An illustration of a tardigrade (water bear) is shown

Water bears can survive temperatures as low as -457 degrees, heat up to 357 degrees and 5,700 gray radiation, while 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 without water for ten years and even survive in space.

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