Bladderwort bladder. Coloured scanning electron micrograph (SEM) of a bladder (centre) of a bladderwort plant (Utricularia sp.). This floating aquatic plant catches tiny invertebrates such as insects in its bladders. Organisms moving past a bladder stimulate trigger hairs around its entrance. The bladder's trapdoor opens inwards, sucking in the prey in around one thousandth of a second. Once digested, the prey provides the bladderwort with the nitrogen which is lacking in the shallow still water in which it lives. Magnification: x38 at 6x7cm size. 60 at 4x5"~SQUARE"