Meet the Water Bear: Toughest Animal on Earth!

Water bear (Macrobiotus sapiens) in moss. Color enhanced scanning electron micrograph (SEM) of a water bear in its active state. Photo by Eye of Science

This “bear” is smaller than a grain of sand, but it’s super tough! Meet the water bear, or tardigrade, a tiny animal found on every continent–and maybe in your backyard! Tardigrades live in films of water on lichen and moss, as well as in ponds and in the ocean. If their moss clumps dry up, terrestrial tardigrades go into a kind of suspended animation called “cryptobiosis.” Tardigrades in this state are called “tuns.” Tardigrade tuns can survive being boiled, frozen, or crushed. When tuns land in moisture, they swell with water and come back to life! Tardigrade tuns have also survived being blasted into space–without spacesuits!

Last week, my friend Cathy and I decided to go hunting for water bears. We gathered moss in her back yard and soaked it overnight in distilled water. The next night, we poured the soaking water into a petri dish and searched for water bears with Cathy’s microscope. Under 20x magnification, we only saw whip-like organisms called nematodes, a mite that looked like a fat spider, and a skinny critter with eight legs and eye spots that we called “eye guy.”

Cathy and I took turns at her microscope. Then I noticed a bit of detritus like a tiny island wobbling around in the petri dish. Suddenly, a creature crawled to the top of it…a water bear! It looked like it was grazing on its teeny detritus island and sniffing around for snacks!

Suddenly, Cathy and I were spotting 4…6…9, water bears through the microscope. We switched to 40x power and got an even better look. Some were clear, some were yellowish, and a few had black smudges like they’d be ambling around in soot!

“It’s a tardi-party!” we exclaimed.

We watched the tardi-party for more than an hour and Cathy gently emptied the petri dish of water back into the moss in her yard. I hope our adventures inspire YOU to go (water) bear hunting–and learn more about these amazing and ancient creatures, who star in my new book Extreme Survivors: Animals That Time Forgot.

This photo of a water bear by Peter Von Bagh gives you an idea of what we saw under the microscope. The tardigrade photo at the top of this post is a scanning electron micrograph (SEM) that has been magnified hundreds of times.

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