What are tardigrades, and why are scientists so interested in these microscopic creatures also known as “water bears”? Recent weeks and months have seen an uptick in interest in these invertebrates, and a new study now suggests that tardigrades just might be tough enough to survive asteroid strikes and other cataclysmic events.
In the words of study co-author David Sloan, a theoretical cosmologist at Oxford University, it’s not accurate enough if you go to the obvious and use humans or dinosaurs as benchmarks for the durability of life on Earth — doing so would make life appear to be “pretty fragile.” Instead, tardigrades may be a much better benchmark, as they may have been among the very first forms of life to emerge on our planet.
Speaking to the Washington Post, University of Stuttgart (Germany) researcher Ralph O. Schill explained what tardigrades are in terms of the noteworthy events in the history of life on Earth they have “witnessed.” Schill, who was noted as an expert on tardigrades, said that microfossils of the species have been dated as far back as the Early Cambrian period, about 520 million years ago. The creatures also may have been around about 100 million years ago, during the Early Cretaceous period, he added.
“They have seen the dinosaurs come and go.”
In terms of their physical appearance, a separate report from Gizmodo described what tardigrades look like — eight-legged creatures that measure only 0.5mm long and are only visible through a microscope. Their durability, on the other hand, can be proved by previous studies, where they survived radiation blasts, freezing temperatures of up to 300 degrees Fahrenheit (150 degrees Celsius), and even intense underwater pressure. As Gizmodo also noted, the animals can live up to 30 years without consuming any food or water.
Those tardigrade facts show us that they are indeed a hardy bunch. But could they survive potentially world-ending events? That was the question scientists wanted to answer in a new study from earlier this week.
In a paper published in the journal Scientific Reports on Friday, Sloan and his fellow researchers described how they tried to do away with tardigrades “in theory,” using sophisticated mathematical modeling techniques to find out if they would survive killer asteroids, supernovae, and gamma-ray bursts — three distinct events considered to be among the most “devastating” our planet may ever witness.
All told, mathematical models suggest that tardigrades are capable of living through 10 billion years’ worth of destructive events, and can potentially survive even if our sun swallows up Earth, or fails completely. None of the aforementioned events were revealed to be likely to boil all of our planet’s oceans, which, in theory, is the only thing that could kill tardigrades and wipe them out completely.
As cited by Gizmodo‘s report, co-author Avi Loeb, an astronomer at the Harvard-Smithsonian Center for Astrophysics, said that tardigrades would react to events that could destroy Earth’s atmosphere by taking refuge in the oceans. That means a complete loss of water would indeed trump any other cataclysmic event when it comes to rendering tardigrades extinct.
There are, however, some possible flaws in the study, according to William R. Miller, a tardigrade expert who was not involved in the research. Miller told the Washington Post that it may have been a mistake for the researchers to bunch all 1,250 tardigrade species into one, for the purpose of their study. According to Miller, not all tardigrades consider the water to be their habitat — some variants, in fact, have been nicknamed “moss piglets,” due to their preference to dwell in moss and lichens.
“I can’t say anything about the physics, but they can’t say anything about the animals,” said Miller.
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