Are tardigrades the most invulnerable animals on Earth?
(ORDO NEWS) — Tardigrades are a group of tiny invertebrate species found all over the world – you can find one on a moss in your garden or in your local park. In fact, you can find them anywhere – on a mountain top, at the bottom of the sea, or even in a volcano!
Astrobiologist Dr. John Stone of McMaster University summarizes how they can survive extreme conditions, including temperatures as low as -180 ° C for 14 days or high temperatures of 151 ° C for 30 minutes.
They can also survive “5000 Gy” gamma rays (this is the type of radiation that turned David Banner into the Incredible Hulk in the Marvel Universe). Where 5-10 Gy kills people, ”says Dr. Stone.
They can also survive in a frozen state for 30 years and potentially up to 100 years, although this is still disputed, writes Dr. Stone.
But are tardigrades the most indestructible animals on Earth? We asked eight biologists studying them – 63 percent answered “Yes,” which means there is still some debate on this issue.
Why are tardigrades so invulnerable?
In difficult conditions for life, tardigrades curl up into a ball called a vat. While in the vat, the tardigrade goes into a kind of “suspended” state called “cryptobiosis”.
During cryptobiosis, animals do not move, grow, or reproduce, but they are protected from extreme conditions. There are several types of cryptobiosis depending on what conditions you face.
The most studied type is called “anhydrobiosis”, which protects cells from drying out in the absence of water.
If cells dry out, their DNA and membranes can be damaged, for example. When some animals undergo anhydrobiosis, their cells are filled with a sugar called trehalose, which protects the contents of the cells until water reappears.
Tardigrades can remain in cryptobiosis without food or water for many years, at least 30 years if frozen.
Other animals that have secrets of cryptobiosis include hookworms, some types of shrimp, and even some types of plants and yeast! Nematodes have been particularly well studied, and paleobiologist Dr. Graham Budd notes that “the record for dehydrated survival belongs to the nematode Tylenchus polyhypnus, which lasted 39 years.”
Despite the controversy, there is no doubt that we are just beginning to understand which creatures can cope with extreme conditions and how they do it.
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