Known usually as the water spider or diving bell spider, it is the only completely aquatic spider in the world. It is found in Europe and Asia, from the UK to Siberia, and lives in ponds, slow moving streams and shallow lakes. Since it cannot take oxygen directly from water, the water spider builds an underwater retreat with silk, and fills it with air it carries from the surface (by trapping air bubbles in the hairs that cover its body and legs). Once filled with air, the silk retreat becomes bell shaped and has a silvery shine, hence the spider's name (Argyroneta means "silvery net"). The spider spends most of its time inside the bell, and only has to replenish the air once in a while. It feeds on whatever aquatic invertebrate they can capture, including backswimmers, water striders and diverse larvae; they also hunt tadpoles and small fish occasionally.