Temperatures as low as -200 °C (-328 °F) and as high as 151 °C (304 °F) Freezing in a block of ice Lack of oxygen for days, possibly months Lack of water for decades Levels of X-ray radiation 1,000 times the lethal human dose Many noxious chemicals Boiling alcohol Low pressure of a vacuum, like that of space Extreme pressure, up to six times greater than found at the deepest part of the ocean Note that they can only survive these conditions in cryptobiosis. If you exposed a living tardigrade to these conditions, it would die instantly.
You can take samples of several different kinds of moss, lichen, or leaf litter to see whether tardigrades like one more than another. Soft lichen is more likely to have tardigrades than hard, crusty lichen. You can even find water bears in the powdery lichen that grows on rocks and brick walls.
If there is a water bear, you’ve struck the jackpot. Pour the water back to the moss to set up a home for it. If you don’t see any after moving the petri dish around for a while, replace the water and try again with a different piece of moss until you find one.
Water Bears also eat nematodes, little worm-shaped creatures, and rotifers, tiny plankton. Try to find nice, wet moss for the Water Bears as that is most likely to contain their prey. Some tardigrades live in freshwater and others live in saltwater. Stick to water and plants from the same type of environment where you collected your tardigrades.
Dried out tardigrades are smaller and completely immobile. You might not be able to spot them, but you’ll see them again if you give them a good soak.
