Several desmids (Micrasterias furcata and M. truncata) were trapped in the bladder trap of the carnivorous waterplant humped bladderwort (Utricularia gibba). Desmids are single-celled algae made up of two mirror-image halves connected at the center. Each half contains a single large chloroplast, which here emits a red fluorescent light. The cells visible in the background are the quadrifid gland cells that line the internal surface of the bladder. These cells pump water out of the bladder, creating a negative pressure inside. When the trap is triggered, the bladder sucks in any tiny organism in the vicinity, like these desmids. Small animals that are trapped generally die of anoxia and are digested. But small algae like desmids can also remain viable inside the bladder.
The desmids and bladderwort trap were stained with a dye to highlight the cell walls (colored green) and imaged with a confocal microscope at a magnification of 200X. The chlorophyll inside chloroplasts was detected by autofluorescence (colored red).
Igor Siwanowicz, PhD, HHMI Janelia Farm Research Campus.