4 Reasons Why Water Bears Are the Toughest Animals on the Planet

On this week’s episode of “Cosmos: A Spacetime Odyssey,” Neil deGrasse Tyson explored the wonders of evolution. Wonderful it is! Life, it turns out, shows up in the wildest places, places only a few decades ago we would never expect. One of the little animals mentioned were tardigrades, otherwise known as water bears, waterbears or, adorably, moss piglets. They are tiny, adorable, micro-animals that only grow to about half a millimeter long. They are also one of the most amazing organisms on Earth. (They’re no slime molds, but then again, nothing is.)

Water bears can live in the vacuum of space

Talk about hardcore. In 2007 some tardigrades got the chance few humans even get: they were sent into space. A lesser creature would have succumbed to the harsh realities of nature outside the Earth’s atmosphere, but not tardigrades. Neither solar winds nor lack of oxygen could kill them off. They just needed a little water and they were back up and running.

Water bears can survive for a decade with basically no water

Basically all life on Earth needs water to survive. Humans are famously three quarters water. Everything needs water. Water bears do, too, but less than most. When it gets very, very cold, their body composition goes from 85 percent water to about 3 percent. During periods of extreme dryness water bears can undergo anhydrobiosis, or life without water. These microscopic organisms can survive in this dry state for 10 years. They do this by curling up into a little ball called a tun. While in its tun state, their metabolism can decrease to about 0.01 percent of the normal level.

Water bears can survive under intense pressure and extreme temperatures

Not only can water bears survive the very low pressure and temperature found in a vacuum, they can also withstand incredibly high temperatures and high pressures. Tardigrades can survive temperatures between -328 F and 304 F. They can even be frozen and thawed and live to tell the tale. The pressures they can tolerate is just as impressive. They can withstand the very small pressures of space, as well as over 1200 times the pressure of the Earth’s atmosphere.

Water bears can tolerate a bunch of radiation

Just mention the word “radiation” and people get all squiggly. Water bears, being the tough little buggers they are, are resistant to radiation. In their chilled state, it took 570,00 roentgens to kill 50 percent of exposed water bears. To put that in perspective, it only takes 500 roentgens to kill a human.

Tardigrades are arguably the toughest animal on the planet, and a marvel of evolution.

Photo Credit: Eye of Science/Science Source Images


Carrie-Anne Brown

thanks for sharing :)

Peter Aldus
Past Member 3 years ago


Elena T.
Elena P3 years ago

Thank you :)

Marianne R.
Marianne R3 years ago


Paula Lambert
Paula Lambert3 years ago

They look like sci-fi creations!

Loraleigh Gill
Diane Gill3 years ago

Hmmm.... tardi (tardis?) grades? Does the Dr have a hand in this?

Anita B.
Anita B3 years ago

I also heard about them at AP. and i love those small creaturs.

brandi bastian
brandi bastian3 years ago

i've heard all this on Most Extreme on Animal Planet... too bad more animals aren't this tough us humans would have a much harder time wiping out species

jayne turner
jayne turner3 years ago

wow! Fascinating!

Fi T.
Past Member 3 years ago

No excuse to keep devastating our homeland