Questions 43-46 Carnivorous plants are various types of flowering plants and fungi that capture and digest prey animals. In order to be classified as carnivorous, plants must fabricate attractants to lure prey, which must be captured and die in their clutches. The prey must also be digested and its nutrients assimilated by the plant. Carnivorous plants use animal nutrients to compensate for low levels of nitrogen and phosphates in their habitat, lack of which inhibits normal processes of photosynthesis. Since the animals they capture are chiefly insects, carnivorous plants are sometimes called insectivorous plants. Some species, however, capture mollusks such as slugs, or even vertebrates such as small frogs and birds. Trap types include pitfalls and “lobster traps,” adhesive traps, and various kinds of mechanical traps. Pitfalls consist of tubular leaves, or arrays of leaves, that are filled with water. Insects are captured when they fall into the fluid, which often contains wetting agents and digestive enzymes. So-called lobster pots also consist of tubular leaves. In this type of trap, however, the tube is often horizontal and is lined with hairs that guide the prey along a path leading to the digestive part of the trap. Adhesive traps exist in several plant families. Typically, flying insects are captured when they adhere to slime secreted by hairs covering the leaf. In some genera, such as Drosera, the leaf actively moves the prey to the center and wraps around it. Sticky-seeded adhesive traps have only recently been observed, but may be widespread. The seed of the shepherd’s purse, Capsera, a common lawn weed, attracts, captures, and utilizes nutrients from prey; soil bacteria do the digesting. Mechanical traps include so-called snap traps, such as those of the Venus’s flytrap. In these plants the prey is trapped by rapid closure of a set of lobes around the animal when it touches sensory hairs that trigger the closure. The action results from acid growth in the lobes within less than a second. Suction traps, found in the aquatic Bladderwort Ultricularia are similar to the style of mouse trap in which a door allows the mouse to enter, but not to exit. The prey trips a lever on the plant “door,” which allows water and the prey to be sucked into the trap when the plant’s concave side puffs outward. Snare traps are found in carnivorous fungi. One type, in the genus Arthrobotrys, has a trap that looks like a small lasso with three segments around the loop. When triggered by a nematode, the segments bulge out to capture the worm. The fungus then grows into the prey and digests it.