Horned Bladderwort
Bladderworts are carnivorous plants. The bladders are in a state of negative osmotic pressure when they are set. Each bladder has a lid with trigger hairs attached. When a small creature brushes by the trigger, a lever-like action takes place. Where the hair attaches to the bladder, it levers an opening in the seal around the lid. Once this seal is broken, the vacuum is released, the lid flies open, and the surrounding water (and its contents) are sucked into the bladder. When the bladder is full, the lid closes. All of this happens in the tiniest fraction of a second.