WEBVTT - How Do Venus Flytraps Work? 0:00:01.840 --> 0:00:07.520 Welcome to Brainstuf, a production of iHeartRadio, Hey brain Stuff 0:00:07.560 --> 0:00:12.640 Lauren volebamb Here. Plants that eat animals may sound like 0:00:12.680 --> 0:00:16.160 the premis for a horror story, but there's nothing supernatural 0:00:16.200 --> 0:00:19.960 about it. Carnivorous plants have existed on this planet for 0:00:20.079 --> 0:00:23.760 millions of years. There are more than five hundred different 0:00:23.840 --> 0:00:28.120 kinds with appetites, ranging from single celled organisms to insects 0:00:28.200 --> 0:00:32.560 to spiders. Today, let's talk about one of the most famous, 0:00:32.960 --> 0:00:38.800 the venus flytrap. The venus flytrap grows roots, stems, leaves, flowers, 0:00:38.800 --> 0:00:42.320 and seeds just like most plants, but it also grows 0:00:42.479 --> 0:00:45.599 two specialized lobes on the end of each leaf that 0:00:45.760 --> 0:00:50.760 form a hinged trap. Those lobes are distinctively green on 0:00:50.800 --> 0:00:53.840 the outside and reddish pink on the inside, with small 0:00:53.880 --> 0:00:57.560 bristles along the edges. But when they're open, they look 0:00:57.640 --> 0:01:01.720 like toothy little mouths calling for a snap. And when 0:01:01.720 --> 0:01:05.319 an insect or a racknid crawls across that pinkish inner surface, 0:01:05.600 --> 0:01:09.240 the trap slams shut and the plant digests its prey. 0:01:09.920 --> 0:01:13.680 It's a mouth and stomach in one. Although the venus 0:01:13.680 --> 0:01:17.560 flytrap has captivated people across the world. Wild populations of 0:01:17.600 --> 0:01:21.199 these plants actually grow in an incredibly small geographic area, 0:01:21.680 --> 0:01:24.320 a region along the coasts of North and South Carolina, 0:01:24.600 --> 0:01:27.440 only some seventy five square miles in area, that's about 0:01:27.440 --> 0:01:31.720 two hundred square kilometers. Their native areas are bogs and 0:01:31.760 --> 0:01:36.120 wetlands that are humid and sunny. They're so scarce that 0:01:36.160 --> 0:01:39.560 some early botanists doubted their existence despite all the stories 0:01:39.600 --> 0:01:44.280 spread about a flesh eating plant. But okay, if other 0:01:44.360 --> 0:01:48.160 plants can thrive on nothing but water, air, nutrients in 0:01:48.200 --> 0:01:52.640 the soil, and some sunshine, why do venus flytraps eat insects? 0:01:54.400 --> 0:01:57.280 Flytraps actually get a good deal of their sustenance just 0:01:57.360 --> 0:02:01.280 like other plants do. During photosynthesis, plants use the energy 0:02:01.320 --> 0:02:03.840 of the sun to drive a reaction that converts carbon 0:02:03.880 --> 0:02:08.280 dioxide and water into sugar and oxygen. The sugar produced 0:02:08.320 --> 0:02:10.520 is then converted to energy that the plant cells can 0:02:10.639 --> 0:02:15.359 use a molecule called adenosine triphosphate or ATP. ATP is 0:02:15.400 --> 0:02:18.720 what our cells used to get stuff done too. However, 0:02:18.919 --> 0:02:22.800 in addition to sugar, plants also need to make amino acids, vitamins, 0:02:22.880 --> 0:02:27.120 and other cellular components to survive in the coastal bogs 0:02:27.160 --> 0:02:30.880 where venus flytraps live, the soil is acidic and minerals 0:02:30.880 --> 0:02:34.760 and other nutrients are scarce. Most plants can't survive in 0:02:34.800 --> 0:02:37.239 this environment because they can't make enough of the building 0:02:37.280 --> 0:02:41.919 blocks necessary for growth. The venus flytrap evolved an alternate 0:02:42.040 --> 0:02:46.040 means of getting those key nutrients. Living creatures like insects 0:02:46.080 --> 0:02:48.120 provide a good source of the stuff that's missing from 0:02:48.160 --> 0:02:53.360 the soil, plus additional carbohydrates so that covers the y. 0:02:53.720 --> 0:02:57.240 But how do these plants catch and eat prey. A 0:02:57.280 --> 0:02:59.960 plant doesn't have a brain or even a nervous system 0:03:00.120 --> 0:03:04.480 to coordinate their functions and movements, nor do they have bones, tendons, 0:03:04.480 --> 0:03:09.720 and muscles to coordinate. But most plants do have some 0:03:09.880 --> 0:03:13.280 way of attracting animals or insects, regardless of whether they're 0:03:13.360 --> 0:03:17.720 going to eat them. Lots of flowering plants have evolved colors, scents, 0:03:17.760 --> 0:03:21.840 and sugary nectar to attract bees, butterflies, and other pollinators. 0:03:22.840 --> 0:03:25.840 In those cases, the animals get a snack, and they 0:03:25.919 --> 0:03:29.520 unwittingly ferry the plant's pollen to neighbors of the same species, 0:03:29.800 --> 0:03:35.080 thus fertilizing them. Hopefully. Similarly, fruits evolved to be sweet 0:03:35.120 --> 0:03:38.040 and tasty because if a bird or other animal eats 0:03:38.080 --> 0:03:41.760 them and later poops the seeds elsewhere unharmed, a new 0:03:41.760 --> 0:03:45.360 plant can grow. In the case of the venus flytrap, 0:03:45.560 --> 0:03:49.080 the inner surface of those specialized lobes secretes a sweet 0:03:49.080 --> 0:03:53.480 nectar that draws in insects searching for food. But the 0:03:53.520 --> 0:03:57.240 inner surfaces of the lobes also sport short, stiff, hair 0:03:57.400 --> 0:03:59.800 like structures that serve as a sort of motion to 0:04:01.520 --> 0:04:05.000 When a creepy crawley crawls across the surface and brushes 0:04:05.120 --> 0:04:09.040 two hairs in close succession or one twice, the lobes 0:04:09.080 --> 0:04:12.240 close down in as little as half a second, trapping 0:04:12.240 --> 0:04:17.480 the creature inside a fun fact or black thereof No 0:04:17.480 --> 0:04:21.599 one knows exactly how this works, ever since Charles Darwin 0:04:21.680 --> 0:04:25.040 described the species in eighteen seventy five, and he called 0:04:25.080 --> 0:04:28.560 it the most wonderful plant by the way. Ever since then, 0:04:28.800 --> 0:04:31.159 researchers have been trying to get to the bottom of 0:04:31.200 --> 0:04:35.320 this trapping mechanism, but it's difficult to observe what's going 0:04:35.360 --> 0:04:38.599 on inside a living plant during half a second of action. 0:04:39.960 --> 0:04:43.800 The prevailing hypothesis goes that a venus fly trap accomplishes 0:04:43.839 --> 0:04:47.640 this feat by rapidly changing the geometry of those specialized 0:04:47.680 --> 0:04:52.440 lobes via water transfer within the lobes upon stimulus. Let 0:04:52.480 --> 0:04:56.919 me break that down, Okay. Each lobe or half of 0:04:56.920 --> 0:05:01.680 a venus flytrap's trap seems to have two functional layers inside, 0:05:02.120 --> 0:05:05.240 an upper layer up against the pinkish interior surface of 0:05:05.279 --> 0:05:08.560 the trap and a lower layer up against the green 0:05:08.640 --> 0:05:13.280 outer surface of the trap. Cells within the layers contain water. 0:05:13.839 --> 0:05:17.960 That's not unusual. Cells generally do contain water, but the 0:05:18.080 --> 0:05:21.200 upper and lower layers are each capable of holding onto 0:05:21.320 --> 0:05:25.960 water and of transferring it quickly to each other. When 0:05:25.960 --> 0:05:28.960 the trap is open. That's actually a tense state for 0:05:29.000 --> 0:05:31.839 the lobes of the leaf, wherein more water is being 0:05:31.880 --> 0:05:37.119 held by the upper interior layer of cells. This makes 0:05:37.160 --> 0:05:41.960 each lobes slightly convex and holds the trap open. But 0:05:42.240 --> 0:05:46.640 when something triggers those motion detector hairs that somehow tells 0:05:46.680 --> 0:05:49.760 the plant to open up pores between the upper and 0:05:49.839 --> 0:05:54.719 lower layers, water quickly moves into the lower outer layer, 0:05:55.120 --> 0:05:59.359 making each lobes lightly concave, curling in around its prey. 0:05:59.520 --> 0:06:03.719 In a fraction of a second, this closed state is 0:06:03.880 --> 0:06:07.280 relaxed for the lobes of the leaf. They open back 0:06:07.360 --> 0:06:10.800 up again by slowly transferring water back to the upper 0:06:10.880 --> 0:06:15.720 interior layer, but it takes a while. Again, no one 0:06:15.880 --> 0:06:18.760 entirely understands how all this works, though there is some 0:06:18.880 --> 0:06:22.880 interesting research into all the biochemical details. But for our 0:06:22.920 --> 0:06:26.320 purposes today, let's focus in on what happens when that 0:06:26.440 --> 0:06:30.960 trap does close on some tasty prey. The lobes of 0:06:30.960 --> 0:06:34.200 the leaf form an airtight seal so that digestive fluids 0:06:34.200 --> 0:06:37.560 and insect parts are kept inside the trap, and so 0:06:37.640 --> 0:06:42.159 that bacteria and molds can't get in. Those toothy looking 0:06:42.200 --> 0:06:44.760 spines on the outer edges of the trap laced together 0:06:45.000 --> 0:06:48.520 and latch the trap shut. There is an upper limit 0:06:48.560 --> 0:06:50.919 to the size of insect that a trap can accommodate. 0:06:51.560 --> 0:06:53.920 The traps will grow up to around an inch long 0:06:54.120 --> 0:06:56.320 or about two and a half centimeters, and in order 0:06:56.360 --> 0:06:59.039 to close tightly, an insect that catches can only be 0:06:59.160 --> 0:07:02.159 about a third of that size. If an insect is 0:07:02.200 --> 0:07:05.120 too large, the trap can't form a seal against microbes, 0:07:05.200 --> 0:07:08.440 which will move in and eat the decomposing insect and 0:07:08.600 --> 0:07:12.040 the trap itself too. The trap will turn black and 0:07:12.160 --> 0:07:17.000 drop off of the plant, but back to dinner. Once 0:07:17.040 --> 0:07:20.120 an insect or a rapnet is firmly ensconced in the trap, 0:07:20.480 --> 0:07:24.640 the process of digestion can begin. The trap now serves 0:07:24.640 --> 0:07:28.160 as a miniature stomach, just like our stomachs. The trap 0:07:28.160 --> 0:07:32.600 secrete acidic digestive juices that do three things. They dissolve 0:07:32.640 --> 0:07:35.400 the soft tissues and sell membranes of the food. They 0:07:35.480 --> 0:07:38.280 serve as an antiseptic to kill any microbes that got 0:07:38.280 --> 0:07:41.800 in with the food, and they break down various proteins 0:07:41.840 --> 0:07:44.760 and other molecules into small pieces that the plant can 0:07:44.760 --> 0:07:48.520 take in. It takes some five to twelve days for 0:07:48.600 --> 0:07:51.600 a trapped digest prey, depending on the size of the prey, 0:07:51.800 --> 0:07:55.480 the age of the trap, and the ambient temperature. Older 0:07:55.480 --> 0:08:00.640 traps and colder temperatures make digestions slower. The process continues 0:08:00.720 --> 0:08:03.080 until all that's left of the insect is its herd 0:08:03.120 --> 0:08:08.520 exoskeleton and its bath of digestive juices. The plant reabsorbs 0:08:08.560 --> 0:08:12.080 the fluids and the trap slowly reopens, after which the 0:08:12.120 --> 0:08:14.760 praise remains are usually either washed away in the rain 0:08:15.040 --> 0:08:18.480 or blown away by the wind. A venus fly trap 0:08:18.520 --> 0:08:20.800 can tell the difference between living prey and a dead 0:08:20.880 --> 0:08:25.200 exoskeleton or other non edible debris that might fall in. 0:08:25.200 --> 0:08:28.559 Inanimate objects that trigger the trap's motion sensitive hairs won't 0:08:28.680 --> 0:08:32.480 keep moving once it slams shut. If there's no further 0:08:32.520 --> 0:08:35.920 stimulation of the hairs, the trap won't seal up, but 0:08:36.000 --> 0:08:38.880 it will be stuck in partially shut state until tension 0:08:38.920 --> 0:08:41.080 can be re established in the lobes of the trap. 0:08:42.360 --> 0:08:45.240 This process takes about twelve hours, at which point the 0:08:45.360 --> 0:08:50.120 unwonted object falls out. This selection process is pretty good, 0:08:50.240 --> 0:08:53.240 but not perfect. While the trap is out of commission, 0:08:53.480 --> 0:08:56.720 real food may be crawling all around the plant. Imagine 0:08:56.760 --> 0:08:58.360 if you had to sit with a chicken bone or 0:08:58.400 --> 0:09:00.840 peach pit in your mouth for twelve hours while the 0:09:00.840 --> 0:09:02.640 rest of your dinner sat on the table in front 0:09:02.640 --> 0:09:06.240 of you. Of course, the venus fly trap doesn't feel 0:09:06.280 --> 0:09:09.280 any kind of way about it. It's a passive participant 0:09:09.280 --> 0:09:13.600 in the process of eating dinner. Any given trap won't 0:09:13.679 --> 0:09:18.000 last the full lifetime of the plant. After about ten 0:09:18.040 --> 0:09:21.480 to twelve closures, either partial or complete, the trap will 0:09:21.520 --> 0:09:26.240 stop trapping and remain partially open. It'll devote its remaining 0:09:26.280 --> 0:09:29.840 time to photosynthesis, usually for around two to three months, 0:09:31.040 --> 0:09:35.720 while our imaginations dream up people eating killer plants. In reality, 0:09:36.000 --> 0:09:38.839 we're the threat to venus fly traps and other carnivorous 0:09:38.880 --> 0:09:42.880 plants in the wild. Venus fly traps today only cover 0:09:43.000 --> 0:09:46.600 about a third of their historic range. In the nineteen seventies, 0:09:46.640 --> 0:09:49.480 there were around four million of them. That's down to 0:09:49.559 --> 0:09:52.360 just over three hundred thousand as of twenty twenty due 0:09:52.400 --> 0:09:55.640 to over collection by humans and the draining and destruction 0:09:55.760 --> 0:09:59.400 of the natural wetlands where they grow. There's a hefty 0:09:59.440 --> 0:10:02.959 fine North Carolina felony charge for removing them from the wild, 0:10:03.360 --> 0:10:07.040 but lots of reputable plant nurseres propagate and sell them legally. 0:10:08.280 --> 0:10:10.320 If you grow one at home, you'll be looking to 0:10:10.360 --> 0:10:15.439 replicate its boggy, bright homeland with specialized soil and humid conditions. 0:10:15.720 --> 0:10:19.520 A terrarium can help. Check growing guides online or talk 0:10:19.559 --> 0:10:23.200 to your local garden center. A venus flytrap will grow 0:10:23.240 --> 0:10:26.720 to about five inches or thirteen centimeters tall, with about 0:10:26.720 --> 0:10:30.120 four to eight traps per plant. You'll want to provide 0:10:30.120 --> 0:10:32.680 it with two or three small flying insects like a 0:10:32.679 --> 0:10:36.400 house fly every month. A far cry from the feed 0:10:36.440 --> 0:10:39.800 me seemore eating habits of carnivorous plants in science fiction. 0:10:44.640 --> 0:10:47.520 Today's episode is based on the article how Venus flytraps 0:10:47.559 --> 0:10:50.719 work on HowStuffWorks dot Com, written by Anne Mieker O'Connell. 0:10:51.600 --> 0:10:54.559 Brain Stuff is production of iHeartRadio in partnership with HowStuffWorks 0:10:54.600 --> 0:10:57.400 dot Com and is produced by Tyler Klain. Four more 0:10:57.440 --> 0:11:01.160 podcasts my heart Radio, visit the iHeartRadio app, Apple Podcasts, 0:11:01.280 --> 0:11:03.160 or wherever you listen to your favorite shows.