Four Deadly Carnivorous Plants

Four Deadly Carnivorous Plants

Posted: August 18, 2016

Anna: They snap, they trap, they stick, and they suck. This is the bizarre world of carnivorous plants—leafy creatures that eat everything from insects, to crustaceans, to mammals.

I’m Anna, and this is Gross Science.

The vast majority of plants only require a few things to survive: sunlight, water, air, and mineral nutrients, which they typically get from the soil or pond water they’re growing in. These nutrients are elements like nitrogen and phosphorus, which are building blocks for things like DNA and proteins. But most carnivorous plants live in places without a lot of nutrients, like peat bogs. So to really thrive, they draw extra nutrition from the bodies of unsuspecting prey.

Now, carnivory has actually evolved multiple times in plants all over the world, giving rise to some wildly diverse and morbidly beautiful methods for catching food. So, Vanessa from BrainCraft and I bought a few carnivorous plants!

Vanessa: They’re so beautiful.

Anna: They really are.

Vanessa: Yeah.

Anna: And I’m going to show you some of my favorites. You ready, Vanessa?

Vanessa: I’m scared and kind of excited all at once.

Anna: Me too! Ok, so first, this is the bladderwort. These guys live in watery environments, but they have these small, empty chambers growing from their stems. When a tiny creature—like a crustacean—passes by, it brushes against these things called trigger hairs. The hairs make the door to the chamber pop open, and as water rushes in to fill the empty space inside, the tiny crustacean gets sucked in, too. This entire process happens in less than a thousandth of a second—the video you’re watching here has been slowed way down. Then the bladderwort releases digestive enzymes into the chamber to break down the insect’s body and lap up its nutrients. After its meal, the chamber squeezes out all the water, closes the door, and is ready to catch more prey.

Vanessa: Wow.

Anna: But that’s only one variety of carnivorous plant. Other types of carnivorous plants act totally differently. For example, the leaves of sundews are covered in delicate, wispy hairs, each with a teeny drop of liquid at the end. Thinking the liquid is actually delicious nectar, insects fly in to grab a tasty drink. But those dewdrops are actually sticky and trap the bug. The wispy tentacles curl around the insect, holding it tightly and maximizing the number of hairs it touches, which speeds up digestion.

Vanessa: What I find so cool is the way sundews operate is like a botanical version of brains and muscles . So, while they don’t have brain cells they do have chemical signals to move which kind of acts as a brain.

Anna: That’s so amazing, it’s a really good analogy. The other really cool thing is that there are actually some carnivorous plants that actually capture prey without moving at all. So, pitcher plants have deep basins filled with digestive enzymes. Insects venture in looking for food, but then they can’t get back out. There are tons of different varieties of these plants, but in this species, called Sarracenia flava, the inside of the pitcher is slippery, so bugs fall in and then can’t crawl up the walls. They also have downward pointing hairs at the bottom of the pitcher that make climbing out even more difficult for the insects. And some species of pitcher plant can catch more than just bugs. Certain tropical pitcher plants are so large that they’ve been known to trap small rodents, like mice and rats.

Vanessa: That’s scary. That’s very scary.

Anna: It absolutely is. But, next is a type of plant that might be a little bit more familiar.

Vanessa: It is more familiar.

Anna: This is the Venus flytrap. These plants have book-like leaves, which emit a sweet smell that attracts insects, like flies. When a fly lands on the leaf, it brushes against trigger hairs. Touching the hair sends a little electric charge through the leaf. And each charge stimulates pores to open, which allow water to move from one part of the leaf to another. The changes in water pressure make the book snap shut in under a second.

However, the plant will only close if at least two hairs are touched in under about 20 seconds—or if the same hair is triggered twice in the same amount of time. Then, the struggling prey needs to touch more hairs before the flow of digestive juices begins. This keeps the plant from wasting precious resources on a false alarm—like a floating speck of dirt or a curious human setting off the snare for fun.

Vanessa: So, when you’re talking about these electrical charges, you’re really referring to something called action potentials. And these are signals our own brains’ neurons use to pass on information to each other. So, we don’t tend to think about it, but it’s kind of amazing how similar we are to plants.

Anna: Yeah, we don’t tend to think about it and that is really amazing. And Vanessa actually has a whole video about this over on her channel, and I’ll put a link to it somewhere on this screen. Definitely go check it out. It’s so cool.

Vanessa: Thank you.

Anna: Anyway, these were just a few examples of the diversity of these deadly traps. But the variety out there is really quite extraordinary—in fact, there are over 750 individual species of carnivorous plants worldwide. And by the way, many of them are easy to find and to care for. So if you have some of these plants at home, let me know. I’d love to see your gruesomely beautiful garden grow.

Vanessa: This one’s really sticky.

Anna: Ewww!

PRODUCTION CREDITS

Host, Writer, Animator, Editor

Anna Rothschild

Original Footage

©WGBH Educational Foundation 2016

Keep an Eye on this One/Another

Walk in the Park

Music Provided by APM

Bladderwort Footage

Courtesy Philippe Marmottant

Venus flytrap catching a fly

Sinclair Stammers/Science Photo Library

Cape sundew engulfing an insect

Francis Chee/Science Photo Library

Bladderwort Traps Prey Light Microscope

Thierry Berrod/Science Photo Library

Spider Trapped in Pitcher Plant

James H. Robinson/Science Photo Library

Sundew Fly Trap Plant

Pond5/GSMotion

Dead Insect Inside Pitcher Plant

Shutterstock/Roger de Montfort

Sarracenia Judith Hindle (4753019871)

Wikimedia Commons/David Eickhoff

Sunset in the Peat Bog (15684909747)

Wikimedia Commons/incidencematrix

AldrovandaVesiculosaHabit

Wikimedia Commons/Jan Wieneke

ByblisLinifloraHabitus

Wikimedia Commons/Denis Barthel

Darlingtonia californica ne8

Wikimedia Commons/NoahElhardt

Uk pond bladderwort2

Wikimedia Commons/Veledan

N. andamana

Wikimedia Commons/Marcello Catalano

Ile de Mahe - Plantes carnivores (3)

Wikimedia Commons/Remi Jouan

Common Bladderwort (3629436369)

Wikimedia Commons/Jason Hollinger

Common Bladderwort

Wikimedia Commons/pellaea

Drosera rotundifolia leaf1

Wikimedia Commons/Petr Dlouhý

Drosera Capensis eating a fruit fly

Wikimedia Commons/Scott Schiller

Pitcher Plants

Flickr/Dave Bonta

Sarracenia leucophylla

Flickr/Aaron Carlson

Sarracenia ‘Boob Tube’ x open-pollinated

Flickr/Aaron Carlson

Sarracenia oreophila x purpurea

Flickr/Aaron Carlson

Pitcher Plants..lots of them!

Flickr/vladeb

IMG_1757

Graeme Scott

Terrestrial shrew remains examined in Nepenthes attenboroughii by Dr Alastair S Robinson

Wikimedia Commons/Alastair S. Robinson

Venus Fly Trap Eating Compilation Scott's Revenge On The Caterpillars

Wikimedia Commons/Scott Schiller

Dionea in action

Wikimedia Commons/Stefano Zucchinali

SFX

Cockroaches

Freesound/StateAardvark­
(used with permission from author)

Squeak Pack/squeak_10

Freesound/Corsica_S

Shuffling Cards

Freesound/robertwulfman

Wink

Freesound/bennychico11

Nord analog howling wind storm

Freesound/medialint

Sniff

Freesound/jrssandoval

Flying Mosquito

Freesound/zywx

Produced by WGBH for PBS Digital Studios

POSTER IMAGE

Drosera rotundifolia leaf1

Wikimedia Commons/Petr Dlouhý

Want more info?

Proceedings of the Royal Society B: Biological Sciences (2011) Ultra-fast underwater suction traps.
http://bit.ly/2a3fVLN

Current Biology (2016) The Venus Flytrap Dionaea muscipula Counts Prey-Induced Action Potentials to Induce Sodium Uptake
http://bit.ly/2a3gy8h

Scienceline: How Does a Venus Flytrap Work?
http://bit.ly/2a3guVU

International Carnivorous Plant Society
http://bit.ly/2a3gV2H