Scientists have now found the genetic answer to why tardigrades are indestructible.
Tardigrades, also known as water bears, are tiny, eight-legged animals that live in places like moss and ponds. Their habitats tend to dry out, and the microscopic animals have evolved to be able to withstand the absence of water. More interestingly, however, is that not only can the tardigrade withstand dehydration, it can also survive the apocalypse. When all is said and done, and the Earth is on the brink of destruction, the tardigrade is likely to survive. The only thing that can kill the tardigrade is the death of the sun.
What makes this small, unassuming animal so hard to break? Its genes, of course. Scientists have put these animals through the ringer—dehydration, desiccation, irradiation, and exposure to a vacuum—and every time, the tardigrade bounced back. What is it about their genes that makes them so indestructible?
First, researchers had to find out what kind of animal a tardigrade is. It has been suggested that the tardigrade is a Frankenstein's monster of sorts—it had parts from two different kinds of creatures. There were suggestions that the tardigrade is a mix between animals and bacteria, but researchers have found that there's no truth to this. They say that findings on the presence of bacterial DNA may have been due to contamination.
A new study claims that there is nothing Frankenstein-like about tardigrade DNA. The researchers found that the tardigrade's closest relatives are arthropods and nematodes. Creatures like spiders and insects are arthropods, while roundworms are nematodes. According to the findings, tardigrades are genetically closest to nematodes, making them more worm-like than insect-like.
The researchers then counted how many HOX genes tardigrades have. HOX genes have something to do with the sequence of segments in different kinds of animals. The tardigrade has five HOX genes, like nematodes. This isn't exactly the most compelling evidence, but most other animals have ten HOX genes instead of five. Of course, it's possible that this is just a coincidence. Then again, it can can also be more evidence of the genetic relationship between tardigrades and nematodes.
The findings tell us that tardigrade genes enable the animal to withstand desiccation, which is the key to the animal's toughness. When the animal is in dry conditions, it triggers a state called anhydrobiosis. When drought sets in, animals go dormant in this state in order to survive. In response, tardigrade genes produce proteins that can replace the water in tardigrade bodies. These proteins dissolve when water returns to the tardigrade's habitat.
What then can this discovery do for us? Unfortunately, it won't be helping scientists figure out a way to make humans more invincible. We'll be vulnerable to a great many things for some time yet. However, this discovery can help us be a little more resilient. The findings can help scientists figure out a way to transport vaccines to remote places without damaging the vaccines themselves. The vaccines can be safely transported across the globe, even without refrigeration. In that way, tardigrades can help make the world a little easier for us to survive.
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