Terrestrial species tend to have tiny traps that feed on minute prey such as protozoa and rotifers swimming in water-saturated soil.

[2] Aquatic species, such as U. vulgaris (common bladderwort), possess bladders that are usually larger and can feed on more substantial prey such as water fleas (Daphnia), nematodes and even fish fry, mosquito larvae and young tadpoles.

[3][4] Bladderworts are unusual and highly specialized plants, and the vegetative organs are not clearly separated into roots, leaves, and stems as in most other angiosperms.

Most species form long, thin, sometimes branching stems or stolons beneath the surface of their substrate, whether that be pond water or dripping moss in the canopy of a tropical rainforest.

To these stolons are attached both the bladder traps and photosynthetic leaf-shoots, and in terrestrial species the shoots are thrust upward through the soil into the air or along the surface.

The aquatic members of the genus have the largest and most obvious bladders, and these were initially thought to be flotation devices before their carnivorous nature was discovered.

They can range in size from 0.2 to 10 cm (0.08 to 4 in) wide, and have two asymmetric labiate (unequal, lip-like) petals, the lower usually significantly larger than the upper.

[2] The flowers of aquatic varieties like U. vulgaris are often described as similar to small yellow snapdragons, and the Australian species U. dichotoma can produce the effect of a field full of violets on nodding stems.

[11] About 80% of the species are terrestrial, and most inhabit waterlogged or wet soils, where their tiny bladders can be permanently exposed to water in the substrate.

[11] Utricularia vulgaris is an aquatic species and grows into branching rafts with individual stolons up to one metre or longer in ponds and ditches throughout Eurasia.

Floating bladderworts in cold temperate zones such as the UK and Siberia can produce winter buds called turions at the extremities of their stems: as the autumnal light fails and growth slows down, the main plant may rot away or be killed by freezing conditions, but the turions will separate and sink to the bottom of the pond to rest beneath the coming ice until the spring, when they will return to the surface and resume growth.

[11] Biogeographic patterns associated with the boreotropic hypothesis[11] lists the origin of Lentibulariaceae to temperate Eurasia or tropical America.

[13] Based on fossilised pollen and insular separation, the last common ancestor of Genlisea-Utricularia clade was found to be a South American lineage that arose 39 mya.

Utricularia probably diverged from its sister genus 30 mya and subsequently dispersed to Australia, represented by subgenus Polypompholyx, and to Africa.

[11] Authorities on the genus, such as botanists Peter Taylor and Francis Ernest Lloyd, agree that the vacuum-driven bladders of Utricularia are the most sophisticated carnivorous trapping mechanism to be found anywhere in the plant kingdom.

The animal which touched the lever, if small enough, is inevitably drawn in, and as soon as the trap is filled, the door resumes its closed position—the whole operation being completed in as little as one-hundredth of a second.

[17] Utricularia have significantly greater respiration rates than most vegetative tissue, primarily due to their complex energy-dependent traps.

Upon triggering, prey is captured through a two-step ATP-driven ion-pumping process where organisms are sucked in by internal negative pressure achieved by pumping water out of the trap and into the external environment.

Recent research suggests that COX subunit I (COX1), a rate limiting enzyme in the cellular respiration pathway associated with the synthesis of ATP, has evolved under positive Darwinian selection in the Utricularia–Genlisea clade.

When there is greater potential change between the lumen and intermembrane space, the leakiness of the electron transport chain also increases, therefore creating a higher production of ROS in the mitochondria of Utricularia.

Therefore, the increased cellular respiration of Utricularia bladders combined with the unique sequestration of protons could lead to its high nucleotide substitution rates, and therefore its wide diversity.

[19] In the 1940s, Francis Ernest Lloyd conducted extensive experiments with carnivorous plants, including Utricularia, and settled many points which had previously been the subject of conjecture.

He proved that the mechanism of the trap was purely mechanical by both killing the trigger hairs with iodine and subsequently showing that the response was unaffected, and by demonstrating that the trap could be made ready to spring a second (or third) time immediately after being set off if the bladder's excretion of water were helped by a gentle squeeze; in other words, the delay of at least fifteen minutes between trap springings is due solely to the time needed to excrete water, and the triggers need no time to recover irritability (unlike the reactive trigger hairs of Venus Flytraps, for example).

[4] He produced suitable artificial "prey" for his experiments by stirring albumen (egg white) into hot water and selecting shreds of an appropriate length and thickness.

[4] Softer-bodied prey of the same size such as small tadpoles could be ingested completely, because they have no rigid parts and the head, although capable of plugging the door for a time, will soften and yield and finally be drawn in.

[4] Very thin strands of albumen could be soft and fine enough to allow the trapdoor to close completely; these would not be drawn in any further unless the trigger hairs were indeed stimulated again.

[4] Lloyd concluded that the sucking action produced by the excretion of water from the bladder was sufficient to draw larger soft-bodied prey into the trap without the need for a second or further touch to the trigger levers.

[21] Trap primordia become spherical in shape, due to growth in both the longitudinal and transverse directions, when UgPHV1 / PHAVOLUTA (PHV) is restricted.

A recent study conducted three cDNA libraries from different organs of U. gibba (~80Mb) as part of a large scale Utricularia nuclear genome sequencing project.

Mutagenic action of enhanced ROS production may explain both high rates of nucleotide substitution and the dynamic evolution of genome size (via double strand breaks).