Some Biologists Aren't Impressed By Apocalypse-Proof Tardigrades
To some scientists, they're just "normal."
It’s no secret that tardigrades, everyone’s favorite microscopic Michelin men, can survive in Earth’s most extreme environments. Whether it’s in the darkest depths of the ocean or the highest peaks of the most fearsome mountains, the molten core of a volcano or the frozen tundra of Antarctica, it’s likely a place they can call home. Some scientists even think they can withstand deep space.
As a result of this reputation, University of Edinburgh tardigrade expert Mark Blaxter, Ph.D., tells Inverse, it’s easy to think these boop-able extremophiles are exceptionally — and uniquely — hardy. While that may be true, its extraordinariness is easily overblown.
Over-excitement about these fire-and-brimstone-loving tardigrades can be seen in the scientific literature, which isn’t always robust. In 2015, a much-hyped study in the Proceedings of the National Academy of Science suggested that as much as one-fifth of the tardigrade genome was “stolen” through horizontal gene transfer from other species, giving the bulky little water bear (real name: Hypsibius dujardini) its wildest traits.
But Blaxter’s new study, published Thursday in the journal PLOS Biology, shows these apocalypse-proof animals are, genetically speaking, pretty “normal” — and that they evolved their super strength entirely on their own, thank you very much.
Extraordinarily cute, but not that special genetically.
Given that tardigrades can dehydrate like a dried mango and, with a squirt of water, pop back to life — sometimes three decades later — it may be hard to believe that tardigrades are just “normal.” But Blaxter, an evolutionary biologist, points out that only a small part of a tardigrade’s genome is dedicated to its ability to survive in the coldest, hottest, highest, and deepest places in the galaxy. The rest of that double helix, he says, is actually dedicated to regular ol’ peeing and pooping.
“There are human beings on the planet who can do amazing things: Climb the highest mountains, sing the nicest songs, write the best press release,” Blaxter says. “But that doesn’t mean the rest of their genome is special.”
Still, if a human ever tried to dehydrate themselves, Blaxter says, our genes would fall apart forever. In tardigrades, however, Blaxter was able to identify in the genome a set of special proteins that are in place to mimic water. When hellfire starts to consume a tardigrade, a switch flips in the animal’s cells, and an H2O-like protein is produced to insulate its genetic material.
And despite earlier research suggesting these genes were the product of theft, Blaxter believes his data shows they evolved naturally. His claims are backed up by other studies that show just 1.2 percent of a tardigrade’s genes are foreign.
Just wanna go BOOP! on this micrograph of a tardigrade with dark green algae in its belly.
But just because its genome is “boring” doesn’t mean the tardigrade isn’t totally rad. In fact, this discovery might make the tardigrade even cooler. Blaxter’s research suggests that, instead of being a petty thief, the “moss piglet” is actually the result of a long, arduous evolution, earning every ounce of our love — and its reputation for indestructibility.
