Tardigrades, commonly called water bears, are pudgy, microscopic (most less than 1 millimeter), 8-legged animals that dwell in vast numbers in moist environments just about everywhere on earth.

World-wide, over 1,000 species have been described. Thus far, with help from DLIA and Dr. Paul Bartels of Warren Wilson College in North Carolina, 80 species have been discovered in the Smokies. 18 of these are new to science and 59 are new to the Park. Amazingly, only 3 species were known to occur in the Park before DLIA and Dr. Bartels began their decade-long inventory.

Tardigrades are most commonly found in association with the water film on mosses, liverworts, and lichens. Despite the common name of "water bear", Individual Tardigrade species only range in size from microscopic up to a mere fraction of an inch. However what they lack in size they gain back our attention in their numbers. Their densities may reach 2 million individuals per sq m (185,874 per sq ft) of moss. Some of the more unusual species live in hot springs, and can withstand other extreme environments through employing a process called cryptobiosis. A few even live in a symbiotic relationship with or on the bodies of other animals. Tardigrades use a pair of oral stylets, or needle-like mouthparts, to pierce the walls of plant cells and feed on the liquid inside. Most species are plant eaters, but some are predators, feeding on tiny invertebrates and bacteria, and a few are detritivores, feeding on dead tissue and debris.