As you might be able to gather, the common bladderwort is an aquatic plant. More than that, it's carniverous! The bladder in its name refers to sacs that line its underwater stem. Tiny animals that touch the bristles near the mouth of the bladders trigger the bladder to open suddenly, with the result that the critter is sucked in. The mouth closes, trapdoor fashion, and the little beast is soon digested.