Carnivorous plantsPlants like the sundew trap their victims with thick, sticky mucilage secreted from specialized glands, which can be quite long. (Photo: Olexandr Taranukhin/Shutterstock)

Many people may be familiar with the sinister jaws of Venus flytraps or even the bulbous pouches of pitcher plants, but the truth is that those species barely scratch the surface of the wonderfully weird world of carnivorous plants.

To be considered carnivorous, a plant must be able to attract, kill, digest and benefit from the absorption of that digestion. There are currently about 630 carnivorous plant species living in the world today, as well as more than 300 protocarnivorous species, which meet some of the aforementioned requirements.

So, what exactly led these fascinating plants to adopt this unique skill set? A recent study published in the journal Nature Ecology & Evolution found that although these plants evolved continents away from each other, they use very similar enzymes to digest their prey. The study also showed that carnivorous plants re-purpose and tweak genes from non-carnivorous relatives in order to digest bugs.

Over thousands of years of evolution, many carnivorous plants adapted to environments where the soil is thin and low in nutrients, so it's not uncommon to find them sprouting from rocky outcroppings or acidic bogs. Same goes for aquatic carnivorous specimens, which aren't rooted at all. Because they don't have to rely on the quality of soil for nutrients as other plants do, they've turned to carnivory to supplement those needs.

There are a variety of trapping strategies employed by these crafty plants, including pitfall traps, snap traps, flypaper traps, bladder traps, lobster-pot traps and even a crazy combination trap called the catapulting flypaper trap.

Continue below to learn more about these highly specialized traps and feast your eyes on some serious carnivorous eye candy.

Pitfall traps

Carnivorous plants: Pitcher plants
Nepenthaceae (upper left and right) are tree-hanging plants, while the cobra lily pitcher plant (bottom left) grows up from the ground. (Photos: Jaime Pharr/Shutterstock, Noah Elhardt/Wikimedia Commons)

These plants trap prey by luring them into a deep leafy cavity filled with viscous digestive enzymes. Once the prey drowns, its body dissolves over time and the resulting nutrients are collected by the plant.

Pitfall traps are found in several plant families — most prominently in the tree-hanging Nepenthaceae (upper left and right) and ground-dwelling Sarraceniaceae (bottom left). What's especially fascinating is that all four families developed the pitfall trap independently of each other, making them a perfect example of convergent evolution.

Flypaper traps

Carnivorous plants: Drosera Drosera or sundews are the one of the largest genera of carnivorous plants. (Photos: Andrew Fletcher, Matthijs Wetterauw/Shutterstock, Noah Elhardt/Wikimedia Commons)

If you've ever dealt with a pesky house fly, then you should be quite familiar with the concept behind this trap mechanism!

These plants trap their victims with thick, sticky mucilage secreted from specialized glands. These glands can be quite long and capable of capturing prey of a significant size, as seen in the sundew genus (above), or they can be very tiny and reminiscent of peach fuzz, as seen in the Pinguicula genus. Either way, any bug or insect that is unlucky enough to stroll across its glue-like hairs won't last long; you can see a fruit fly meet its demise in the video below.

Scientists speculate that one of the pitcher plant families, Nepenthaceae, may have actually evolved from the common ancestor of contemporary flypaper traps.


Snap traps

Carnivorous plants: Venus flytrap The Venus flytrap, found in subtropical wetlands of the eastern North American coast, may be the most well-known carnivorous plant. (Photos: Caroline K. Smith MD, Number One, AlessandroZocc/Shutterstock)

When one thinks of "carnivorous plants," the infamous Venus flytrap is often the first image to come to mind. Found in the subtropical wetlands of the eastern North American coast, these iconic snap traps are highly specialized for catching insects and spiders at rapid speeds.

To ensure that the Venus flytrap doesn't waste precious snapping energy on objects with no nutritional value that just happen to fall between its leaves, the plant employs a "redundant triggering" mechanism. That is, the leaves only close if two separate trigger hairs are touched within 20 seconds of each other.

Check out the video below to see these hungry plants in action:

Although the Venus flytrap has a tendency to hog all the glory, it's not the only snap trap on the block. The aquatic waterwheel plant is capable of trapping small invertebrate organisms using two lobes with very fine trigger hairs that can snap the trap shut in just 10-20 milliseconds. This species is the most widely distributed carnivorous plant species on the planet, but it has become quite rare over the past century and is currently listed as endangered.

Catapulting flypaper trap

Carnivorous plants: Combination flypaper and snap trap Drosera glanduligera possesses both flypaper and snap-trapping abilities. (Photo: MFdeS/Wikimedia Commons)

One carnivorous plant species, Drosera glanduligera, possesses both flypaper and snap-trapping abilities. Endemic to Australia, this peculiar plant captures its prey with its delicate outer tentacles. When an object puts pressure on these tentacles, plant cells break underneath it and send the object catapulting towards the center of the plant.

In the video below, witness some unwitting fruit flies falling into this plant's tentacled clutches.

Bladder traps

Carnivorous plants: Bladderwort There are more than 200 species of bladderworts in the genus Utricularia. (Photos: BMJ/Shutterstock, pellaea/Wikimedia Commons)

This kind of carnivorous plant trap occurs in just one genus: Utricularia, commonly known as bladderworts. There are more than 200 species of bladderworts all over the world, including both terrestrial and aquatic varieties.

While the terrestrial bladderworts trap and feed off tiny protozoa and rotifers navigating their way through moist soil, aquatic bladderworts are capable of capturing larger prey, including nematodes, water fleas, mosquito larvae, young tadpoles and more.

Don't let their size fool you — bladderwort traps are surprisingly complex and considered to be one of plant kingdom's most sophisticated structures. For example, in the aquatic species, any prey that triggers the hairs surrounding the plant's "trapdoors" is literally sucked into the bladder by negative pressure. Once the remainder of the space in the bladder is filled up with water, the door shuts.

Lobster-pot traps

Carnivorous plants: Genilisea Lobster-pot traps get their name because, similar to the traps used by lobster fisherman, it's easy for prey to fall into the trap but difficult to exit. (Photos: Noah Elhardt, Dennis Barthel/Wikimedia Commons)

The corkscrew plants of the Genlisea genus, which are found in moist terrestrial or semi-aquatic environments, were only officially proven to be carnivorous in 1998.

The main mechanism used to capture prey are a set of Y-shaped subterranean leaves that appear white due to the lack of chlorophyll. Although the plant is rootless, the underground leaf traps do serve functions that are very root-like, including water absorption and anchorage.

It's called a "lobster-pot trap" because — similar to the traps used by fishermen to catch actual lobsters — it's very easy for prey (in this case, aquatic microfauna such as protozoans) to stumble into the plant's trap, but very difficult for anything to exit due to the spiraled structure of the leaves that force movement of the microscopic victims toward digestion.

Editor's note: This story has been updated since it was originally published in December 2014.

Catie Leary ( @catieleary ) writes about science, travel, animals and the arts.