Tardigrades are great at adapting to harsher environments. Anhydrobiotic tardigrades can survive undamaged for many years without absorbing water, which was proved by a professor back in 2019. It was not clear if they age faster or slower in a frozen state. The frozen tardigrades are not old.
Water bears, also known as tardigrades, are part of the family of Nematos. The only similarity between them and a bear is the way they walk. The tardigrades, which are barely one millimeter in size, have adapted to rapidly changing environmental conditions over the course of evolution and can dry out in extreme heat and cold. Schill says that they fall into a deep sleep.
There is a sleeping beauty hypothesis.
Stress can be caused by freezing or drying out a cell. Tardigrades can survive both warm and cold. There are no obvious signs of life left. The question of what happens to the animals' internal clock and whether they age in this resting state is raised.
The question of aging for dried tardigrades was answered several years ago by Ralph Schill and his team. The princess falls into a deep sleep in a fairy tale. When a prince kisses her 100 years later, she awakens and still looks like her old self. The "Sleeping Beauty" hypothesis is that it is the same with tardigrades when they are dried.
Schill explains that during inactive periods the internal clock stops and only restarts once the organisms are activated. Tardigrades, which only live for a few months without periods of rest, can live for a long time.
It wasn't clear if this applies to frozen animals. Is aging the same as the dried animals, or is it different?
Even when it's frozen, the aging process doesn't stop.
Schill and his team conducted several experiments in which they froze more than 500 tardigrades, counted them, fed them and froze them again. All the animals died. Control groups were kept at the same temperature. The comparison with the control groups showed the same lifetime. Even in ice, tardigrades stop their internal clocks.
Schill and his colleagues published their findings in a journal.
More information: J. Sieger et al, Reduced ageing in the frozen state in the tardigrade Milnesium inceptum (Eutardigrada: Apochela), Journal of Zoology (2022). DOI: 10.1111/jzo.13018 Journal information: Journal of Zoology
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