Bladderwort bladder. Coloured scanning electron micrograph (SEM) of the entrance to a bladder of a bladderwort plant (Utricularia sp.). This floating aquatic plant catches tiny invertebrates such as insects in its bladders. Organisms moving past the bladder stimulate trigger hairs (stalks with spherical ends) 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: x335 ay 6x7cm size. x520 at 4x5"~SQUARE"