by Tim Pearce
Water bears, also known as tardigrades or moss piglets, are microscopic animals, famous for being cute and nearly indestructible. Looking a bit like the Michelin Man with eight claw-tipped legs, they can survive extreme highs and lows of temperature and pressure, and ionizing radiation. They are among the few animal groups that can completely dry up into suspended animation, a process called anhydrobiosis, and tardigrades can survive dried up for decades. Tardigrades have even survived in outer space (see “Tardigrade” in Wikipedia for more amazing feats).
Large ones can be 1 mm (1/25 inch) long, but most species are less than half that long. They live in many environments, and can often be found in moss and lichen. I even saw some tardigrades digesting the waste stream during an open house at ALCOSAN, Pittsburgh’s sewage treatment plant.
To practice for the 2021 City Nature Challenge, I looked for tardigrades in my back yard. I scraped up a bit of moss, shook it in some water, and then examined the settled material under a microscope. Within a few minutes, I had found the tardigrade illustrated here! I also saw nematodes and rotifers, two other common microscopic organisms. I just checked iNaturalist, and no tardigrades have been reported from Pittsburgh, so mine will be the first!
How does finding tardigrades make my yard like the moon? You might remember in 2019 an Israeli lunar probe crashed on the moon. Part of its payload was dehydrated tardigrades, which evidently have been scattered across a section of the lunar surface. My yard is like the moon because they both have tardigrades!
Examining the world of the small can yield big contributions. I encourage you to participate in the City Nature Challenge, and pay attention to tiny things.
Tim Pearce is the head of the mollusks section at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.
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Carnegie Museum of Natural History Blog Citation Information
Blog author: Pearce, TimothyPublication date: April 29, 2021
