Water bears and water loss: Tardigrades and anhydrobiosis

The Phylum Tardigrada consists of about 900 known species of microscopic animals that are often referred to by their endearing popular names, water bears or moss piglets (translated from the German expressions Wasser Bär and Mooschweinchen). The group is considered a sister group to the arthropods, with animals typically less than 0.5 mm in length1. As tardigrades are of no direct medi cal or agricultural importance, their study is confined to a small, but highly productive, international community of researchers.