Term:

Bladder
Definition:

A thin-walled, inflated, small sac found in species of . The function of these sacs is to capture very small organisms, such as mosquito larvae, which are decomposed and the nutrients (e.g., nitrogen) released are then assimilated by the plant.
Notes:

The bladder-bearing species of Utricularia are carnivorous plants. When the trigger hairs (= trichomes) are touched by prey, a trap door into the bladder opens and the prey are "vacumed" into the bladder where they are decomposed and then the nutrients released are assimilated by the plant; thus, bladderworts do not "eat" the prey. The species found floating in water have larger bladders (up to 5 mm diam.) whereas terrestrial species have smaller ones. The ones with larger bladders capture animals such as copepods and mosquito larvae while the smaller ones capture smaller prey such as protozoans and rotifers.