It is known as the ‟humped bladderwort,‟ for the shape of irs trap. It is a carnivorous plant. Charles Darwin had the insight that this feeding style answers the need by plants for nitrogen.
A carnivorous annual plant, it can be found in bogs, in pools of stagnant water or wet soil where it feeds on small insects and larvae. In evolutionary terms, it derives from the tomato and grape. It diverged from the former, Solanum, about 120 Mya (million years ago) and from the latter ancestor, Vitis, about 83.6 Mya. Since that second divergence, Utricularia gibba underwent three whole-genome duplication events. Its genome, among flowering plants, is the smallest reliably assembled, with about 80 megabases only. It consists near-exclusively of meaningful, protein-coding, genes.
The genus Utricularia comprises about 215 species. Their name derives from the Latin utriculus, meaning wine flask— as in the biblical phrase, ‟you cannot put the new wine in old flasks.‟
They can be found on every continent, with the exception of Antarctica. They occur in fresh water and wet soil as terrestrial or aquatic species.
Terrestrial species tend to have tiny traps that feed on minute prey such as protozoa and rotifers swimming in water-saturated soil.
There are no roots. Flowers are the only part of the plant clear of the underlying soil or water. They are usually produced at the end of thin, often vertical inflorescences. They can range in size from 2 mm to 10 cm wide.
Numerous species of insects visit Utricularia flowers and pollinate them.
These plants supplement their photosynthetic nutrition by trapping various microscopic prey animals.
One strolls by a pond. The scenery is bucolic. Butterflies flutter in the sunshine. Mosquitoes may be about. The ears cocked for them listen to birdsong. Nature at its best, seemingly. A serene feeling of harmony and calm. Yet, beneath the placid surface, furies unleash themselves.
The lenticular Utricularia trap has a two-phase mechanism of remarkable simplicity. During the first, slow phase, which lasts about one hour, glands actively pump water outside the trap interior. The attendant reduced hydrostatic pressure stores elastic energy inside the trap, that then shows concave wall curvatures. The bladder stores potential energy like a spring. Eventually, no more water is expelled, and the bladder trap is ‘fully set.’ In its buckling-unbuckling process, it resembles an inside-out tennis ball.
A flexible door with levers closes the entrance watertight. By brushing against these triggering hairs, prey animals activate their doom : the triggering results in door opening, trap wall relaxation and water (and thereby prey) influx due to the sudden increase of the trap volume. This second phase is ultrafast, it lasts less of a millisecond. It is reportedly the fastest motion plants are capable of. After the door closes again, the prey is gradually dissolved by digestive enzymes.
And the whole process can restart. An impressive catch of fresh food by the plant, death throes for the prey: nature at its most efficient,and grim.