Tardigrade waterbear tun (Echiniscus testudo) Science Image

Ref: 80017085



Water bear. Coloured scanning electron micrograph (SEM) of a water bear (Echiniscus testudo) in its cryptobiotic tun (or barrel) state. The water bear (or tardigrade) is a tiny invertebrate that lives in coastal waters and freshwater habitats, as well as semi-aquatic terrestrial habitats like damp moss. It requires water to obtain oxygen by gas exchange. The tun state is a response to a period of dessication. It contracts and extrudes a wax covering as its metabolism drops to near-zero. Addition of water will revive it. The tardigrade feeds on plant and animal cells. It is found throughout the world, from the tropics to the cold polar waters. Magnification: x455 at 6x7cm size.