The distribution and ecology of Tardigrada in interstitial habitats in northern Europe is discussed. Known results point only to species of the genera Macrobiotus and Hypsibíus (fam. Macrobiotidae) as being psammophilous. Fourteen species were found; of these six belong to the genus Macrobiotus and eight to Hypsibius. Three species from each genus are new. Adaptations of true freshwater Tardigrada are discussed, the major aspect of which is the development of prehensile claws.