Tardigrades Can Survive Frozen Oblivion by Pausing Their Biological Clocks

Tough tardigrades, like the title character in the classic fairy tale Sleeping Beauty, can stop their biological clock in a deep, cold sleep.

These beasties have a variety of powers that they use to survive, including armor to protect their genes from radiation and a special padding that protects their cells from dehydration.

They can survive with this bag of tricks.

Cryobiosis is an extreme form of hibernation that water bears use to survive the cold. Their metabolism stops functioning in this state.

Their metabolism isn't the only one that's going to stop.

A bunch of Milnesium inceptum tardigrades were exposed to alternating weekly periods of freezing at 30 C and feeding at 20 C. The group was kept at a certain temperature.

Those that were periodically frozen lived twice as long as the control group. The oldest tardigrade in the control group was 93 days.

Both groups spent the same amount of time alive, showing that the tardigrade's biological aging was slowed if not halted altogether. The'sleeping beauty' model of cryobiosis on the animal's biological clock supports the idea that aging is slowed or continues as normal.

"During inactive periods, the internal clock stops and only restarts once the organism is activated," says zoologist Ralph Schill. Tardigrades, which only live for a few months without periods of rest, can live for a long time.

Under extremely dry conditions, these cute near-immortals go into a suspended animation state. This is the first time that tardigrades have been confirmed as suspending their aging during this state.

The millimeter-sized beasts are able to wait out hazardous conditions and come back into action once their surroundings are better. The true love's kiss that woke Sleeping Beauty was replaced by the return of rain.

The tardigrades were frozen for more than 30 years. Their suspended animation is not a sure fire way to go.

It is difficult to freeze safely. The researchers say that death can occur if freezing happens too fast.

It's possible that insufficient energy storage can go very wrong. In previous studies, it has been shown that entering and exiting their sleep state uses the energy stored in their cells.

The life cycle patterns of invertebrates are determined by the severity, unpredictability and variability of the environment.

The journal of zoology published this research.