A microscopic creature known as a tardigrade, sometimes called a water bear, is extremely tough and resilient. They are so tough and resilient that NASA studied the microscopic creatures to find out how they can survive incredibly harsh conditions such as decades of freezing or direct exposure to the vacuum of space. The tiny creatures were thought to be the toughest on the planet, but there is one creature that could be even tougher.
The creature is called the Bdelloid rotifer and is being revived after being discovered frozen in the Siberian permafrost for the past 24,000 years. Not only did the tiny creatures survive after thawing them after this period of time, they also began to reproduce immediately when thawed. The creatures survived the freeze by immersing themselves almost completely in a state called cryptobiosis.
Creatures are also able to survive when dehydrated, starved, and exposed to low oxygen levels. Researchers on the project say the report is the toughest evidence yet that multicellular animals could survive tens of thousands of years in cryptobiosis, a state of almost completely stopped metabolism. The sample in which the rotifers were discovered was dug from the ancient permafrost in Siberia with a drill.
Scientists on the project previously identified many unicellular microbes in the samples. For example, it has been reported that a 30,000 year old nematode worm was discovered along with mosses and some plants that were regenerated in the ice after thousands of years.
In the past, rotifers have been reported to survive for up to a decade when frozen. The new study used radiocarbon dating to determine that the rotifers recovered from the permafrost were approximately 24,000 years old. The rotifers in question belong to the genus Adineta and can reproduce in a clonal process known as parthenogenesis. The study showed that rotifers can withstand the formation of ice crystals during slow freezing. It suggests that the creatures have a mechanism to protect their cells and organs from damage at extremely low temperatures. This exact mechanism is a mystery.
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