Overview
Tardigrades means slow walkers. The common name is "water bears". About 90 species are known in New Zealand.
Water bears are very small (0.1 to 1.2 mm long), with elongate, "sausage"-shaped bodies, and eight legs with claws. They are found everywhere in the world, in all habitats, and can withstand environmental extremes (freezing or drying) by entering a state of suspended animation called cryptobiosis. They can reduce the water content of their body from 85% to just 3%, becoming barrel-shaped and forming a cyst or “tun”. In this state, they can survive for many years, even centuries, becoming active again when moisture is available.
There are more than 750 described species of tardigrades, ranging in length from 100 to 500 millionths of a metre, and a few may reach 1200 millionths of a metre long. Their bear-like appearance - legs with claws, and slow side-to-side lumbering gait - give them the common name of water-bears.