Water Bears belong to a lesser known phylum of invertebrate animals, the Tardigrada. The first tardigrades were discovered by Goetz in 1773. Over 400 species have been described since that time.
Tardigrades grow only to a size of about 1mm, but they can easily be seen with a microscope. Tardigrade bodies are short, plump, and contain four pairs of lobopodial limbs (poorly articulated limbs which are typical of soft bodied animals). Each limb terminates in four to eight claws or discs. They lumber about in a slow bear-like gait over sand grains or pieces of plant material.
Scientists figured out why
tardigrades are nearly impossible
to kill with radiation. They
discovered a protein, Dsup, that
covers tardigrades’ DNA and
shields it from radiation. According
to the study, Dsup could also help
protect humans from the deadly
radiation in interplanetary space. SourceSource 2
Tardigrades, aka Water Bears, are a type of extremophile, a name that’s well-deserved. Tardigrades are able to go into what’s called a ‘tun state’ where they become virtually invincible. They’ve survived the vacuum of space and extreme radiation, they’ve been dried out and resurrected decades later, they handle boiling temperatures and deep freezing down to 1 degree Kelvin (molecular motion stops at 0 degree Kelvin) and they’ve managed to look adorable and cuddly while doing it! Basically, Water Bears are the most badass microorganism around. Don’t mess with Water Bears.
Tardigrades reproduce sexually and females lay eggs. She’ll actually shed her skin first and then lay her eggs inside of it. The babies then hatch from their eggs and then have to crawl out of the skin husk. Fun fact: tardigrades are born with the same number of cells as their adult counterparts - their cells just get bigger as they age.
In 1983, Japanese scientists accidentally
scooped up two tardigrades and an egg when they were collecting a sample
of moss. Scientists stored the organisms at minus 4 degrees Fahrenheit. One tardigrade and the egg lived and are now slowly coming back to life. Could this lead to breakthroughs in cryonics?
Inside the Bizarre Genome of the World’s Toughest Animal
Tardigrades are sponges for foreign genes. Does that explain why they are famously indestructible?
by Ed Yong
The toughest animals in the world
aren’t bulky elephants, or cold-tolerant penguins, or even the famously
durable cockroach. Instead, the champions of durability are endearing
microscopic creatures called tardigrades, or water bears.
live everywhere, from the tallest mountains to the deepest oceans, and
from hot springs to Antarctic ice. They can even tolerate New York. They
cope with these inhospitable environments by transforming into a
nigh-indestructible state. Their adorable shuffling gaits cease. Their
eight legs curl inwards. Their rotund bodies shrivel up, expelling
almost all of their water and becoming a dried barrel called a “tun.”
Their metabolism dwindles to near-nothingness—they are practically dead.
And in skirting the edge of death, they become incredibly hard to kill.
the tun state, tardigrades don’t need food or water. They can shrug off
temperatures close to absolute zero and as high as 151 degrees Celsius.
They can withstand the intense pressures of the deep ocean, doses of
radiation that would kill other animals, and baths of toxic solvents.
And they are, to date, the only animals that have been exposed to the
naked vacuum of space and lived to tell the tale—or, at least, lay
viable eggs. (Their only weakness, as a researcher once told me, is
“vulnerability to mechanical damage;” in other words, you can squish
Tardigrades, or water bears, are pudgy, microscopic animals that look
like a cross between a caterpillar and a naked mole rat. These aquatic
invertebrates are consummate survivors, capable of withstanding a host
of extremes, including near total dehydration and the insults of space.
Now, a paper1 published on 20 September in Nature Communications
pinpoints the source of yet another tardigrade superpower: a protective
protein that provides resistance to damaging X-rays. And researchers
were able to transfer that resistance to human cells.
“Tolerance against X-ray is thought to be a side-product of [the] animal’s adaption to severe dehydration,”
says lead study author Takekazu Kunieda, a molecular biologist at the
University of Tokyo. According to Kunieda, severe dehydration wreaks
havoc on the molecules in living things. It can even tear apart DNA,
much like X-rays can.
Meet the tardigrade—a tiny, nearly indestructible creature, and one of the stars of the upcoming exhibition, Life at the Limits: Stories of Amazing Species, opening 4/4. Typically found near water, tardigrades can survive just about anywhere, from the bottom of the ocean, to a Himalayan mountain, to the surface of a glacier. “They can survive the loss of almost 100% of their water,” said Dr. Mark Siddall, a parasitologist and curator of the upcoming exhibition. Tardigrades even survived when they were blasted into space and left outside in the subzero, oxygen-deprived vacuum for 10 days. Pictured is Paramacrobiotus craterlaki, a carnivorous tardigrade found living in moss at a crater lake in Kenya.