Diving bell spiders (Argyroneta aquatica) can use air bubbles to breathe underwater, essentially treating them like mini scuba-diving tanks. The spiders are tiny, measuring just 0.4 to 0.6 inches (10 to 15 millimeters) long, so one bubble can supply more than a day's worth of air. German scientists mimicked extreme low-oxygen conditions in a lab and watched the clever critters construct webs between pondweeds and aquarium sides, and then collect large air bubbles on their abdomen and rear legs.