Water bear (or tardigrade). Scanning electron micrograph of a water bear (echiniscus granulatus). These tiny invertebrates live in coastal waters and freshwater habitats, as well as semi-aquatic terrestrial habitats like damp moss. They require water to obtain oxygen by gas exchange. In dry conditions, they can enter a cryptobiotic tun (or barrel) state of dessication to survive. Water bears feed on plant and animal cells and are found throughout the world, from the tropics to the cold polar waters. When in the dessicated state they can survive extreme environments including up to 10 days in the vacuum of space and are classed as extremeophiles. Magnification x2100 (x520 at 10cm wide).