The only carnivorous plant with a true “trapdoor” is the remarkable bladderwort (Utricularia). This little submersed aquatic plant has one of nature’s most precise and delicate traps, and certainly the most rapid. Thousands of minute bladders are attached to feathery submersed branchlets by tiny stalks. At one end of each bladder is an opening and a flap of tissue which forms the door. The door hangs down from the top of the entrance like a garage door, except it opens inward.

The airtight door is hinged to allow easy entry but it cannot be forced open from within. Special trigger hairs near the lower free edge of the door cause it to open. When a minute aquatic organism touches or hits one of these extremely sensitive hairs, the hair acts as a lever, multiplying the force of impact and bending or distorting the very pliable door. This breaks the watertight seal and, since the bladder contains a partial vacuum, the hapless victim is sucked in. The whole trapping process occurs within 15 to 20 milliseconds (about 1/60 of a second), roughly the speed of a daylight camera shutter setting.

Categories: Plants