All living organisms need food. Plants are able to make their own food through photosynthesis - a process used by plants and other organisms to convert the light energy captured from the sun into chemical energy. But animals must rely on plants either directly (herbivores) or by eating other creatures that eat plants (carnivores). Without plants, animals would be unable to survive. But some plants have turned the tables and have evolved to ‘eat’ animals! You might be wondering, why would a plant need to ‘eat meat’? These plants have leaves and are able to photosynthesize. Photosynthesis fulfills a good bit of their need for energy, but plants do not rely on glucose (the product of photosynthesis) alone. Plants (like all living things) also need other nutrients and minerals, proteins and amino acids. Most plants are able to uptake these through their roots often in association with symbiotic fungi. But carnivorous plants tend to live in areas where the soils are very shallow to non-existent, or in boggy places where nutrients are often leached away. These plants have developed an edge and can inhabit ecological niches where other plants cannot survive. Over 600 species of carnivorous plants have been identified and they inhabit every continent but Antarctica. But it turns out that North America has the greatest diversity of carnivorous plants in the world. Carnivorous plants have special adaptations that lure in prey to supply the needed nutrients. They attract, trap, and digest prey! And prey can be anything from small insects, frogs, and lizards to birds and small mammals. A recently discovered pitcher plant from the Philippines, Nepenthes attenboroughii (named for Sir David Attenborough), has pitchers large enough to entrap rats. Human imagination has embraced and embellished on the mythology of these plants, but there are no known species that prey upon Homo sapiens! The five types of carnivorous plant traps are snap traps, flypaper traps, pitfall traps, bladder traps and lobster traps. Perhaps the most famous carnivorous plant is the Venus flytrap (Dionaea muscipula) shown on the left. This is the plant that inspired Howard Ashman’s creation Audrey II in ‘Little Shop of Horrors.’ This plant is native only to North and South Carolina, USA where it inhabits nitrogen and phosphorus poor bogs and wetland savannahs. But it has become naturalized in similar habitats from Florida to New Jersey. The Genus name, Dionaea refers to the Greek goddess Aphrodite, daughter of Dione. The species epithet ‘muscipula’ is Latin for mousetrap. But in fact, the Venus flytrap’s diet is made up of beetles, spiders and arthropods. It is an example of the snap trap. The ‘traps’ of a Venus flytrap have anthocyanins (red or purple pigments) that attract many insects; they also secrete mucilage, a protein that many insects feed upon. Three “hairs” inside the trap act as a trigger and control the snapping; when stimulated, the trap snaps closed within a fraction of a second trapping the prey for digestion. Next occurs the tightening stage where over a period of minutes, the trap is closed down further. With each brush of a trigger hair by the struggling prey, the trap is stimulated to tighten and close down further. Once the prey is caught and secured, the sealing phase begins, with the plant folding upwards and outwards the teeth that helped to trap the prey. And the rims of the trap are compressed tightly together to form a seal. Once the seal is established, the plant begins to secrete the digestive juices drowning the insect prey. Digestion may take from 5 to 12 days depending upon the size of the prey. Once digestion is complete, the plant resorbs the digestive juices and opens the trap back up to attract new prey. The other type of carnivorous plant known to use the snap trap is the waterwheel plant Aldrovanda vesiculosa. With only a single extant (living) species spread across Europe, Africa, Asia and Australia, there are currently only 50 confirmed populations worldwide. Sundews and butterworts use the flypaper trap approach to capture prey. Sundews are the largest genera of carnivorous plants and are distributed globally. Sundews also secrete mucilage to attract insects. This mucilage gives the plant its glistening appearance and is responsible for the genus name Drosera, Greek for ‘dewy.’ Sundews have leaves that form prostrate or upright rosettes. These leaves have adhesive hairs that function as flypaper. Prey trapped by the hairs either succumb to death through exhaustion or through asphyxiation as the mucilage envelops them, with death usually occurring within 15 minutes. While the insect is dying, the plant secretes digestive enzymes that dissolve the insect and frees the contained nutrients. The nutrient soup is then absorbed through the leaf and used to help fuel plant growth. Butterworts employ similar tactics to those of the sundews. They are found globally, but Central and South America harbor the bulk of the species. Many butterworts cycle between rosettes composed of carnivorous and non-carnivorous leaves as the seasons change. Below from left: round-leaved sundew (Drosera rotundifolia) from Massachusetts, USA; butterwort (Pinguicula moranensis) from Germany; pink rainbow (Drosera menziesii), a species of sundew indigenous to the swamps of Western Australia. Pitcher Plants are so named for the distinctive “pitchers” or cup-like formations used for trapping insects. These plants use the pitcher as a pitfall trap. They attract insects with a sweet smelling nectar and when an insect lands on the smooth, vertical surfaces, it falls down inside. Furthermore, many pitcher plants have transparent regions that make it confusing to an insect as to where to escape. There are two major families of pitcher plants; Sarraceniaceae, the marsh and bog dwellers of North and South America, and Nepenthaceae, residents of the tropics of Southeast Asia, Australia, India, and Madagascar. Sarracenia species rely upon symbiotic bacteria to digest and absorb the nutrients. Many Nepenthes species are capable of digesting their own prey but also establish symbiotic relationships with specific animal species (e. g. ants,) that go beyond nutrient sharing. Below, this unfortunate bee has fallen victim to a white trumpet pitcher plant (Sarracenia leucophylla); pitcher plant (Nepenthes alata) from the Philippines. Bladderworts employ a tactic known as vacuum-suction and are called bladder traps. Terrestrial species are generally visible only while they are in flower, while aquatic species can be observed below the surfaces of ponds and streams. Bladderworts occur in fresh water and wet soil as terrestrial or aquatic species across every continent except Antarctica. The extremely sensitive ‘bladders’ of these rootless plants, suck insects inside the plant by a vacuum and then digest the food. Members of the genus Genlisea, the corkscrew plants, distributed throughout Africa and Central and South America employ the lobster trap method to catch prey. A lobster-pot trap is a chamber that is easy to enter, and whose exit is either difficult to find or obstructed by inward-pointing bristles and a Y-shaped modified leaf that allows prey to enter but not exit. The delicate flowers of the little floating bladderwort (Utricularia radiata) from Canada, and the pretty bladderwort (Utricularia sp.) from Thailand on the right, belies their deadly reputation; center, the unusual flowers of the sweet pitcher plant (Sarracenia rubra) from North Carolina. In addition to the carnivorous plants, there are about 300 plant species that exhibit some characteristics typical of carnivorous plants called protocarnivorous plants, meaning ‘almost carnivorous.’ But that is a topic for another day. Who knew that plants could lead such interesting lives? Lisa Powers