Also known as water bears, tardigrades are microscopic eight-limbed invertebrates inhabiting moist environments. The world´s largest tardigrade is Echiniscoides sigismundi, a marine Eurasian species, which can attain a total length of 1.5 mm as a mature adult (unlike most other species, which remain microscopic throughout their lives). However, it can be smaller than 0.05 mm as a freshly-hatched larva.