Speaker 1: Welcome to Brainstuf, a production of iHeartRadio, Hey brain Stuff
Speaker 1: Lauren volebamb Here. Plants that eat animals may sound like
Speaker 1: the premis for a horror story, but there's nothing supernatural
Speaker 1: about it. Carnivorous plants have existed on this planet for
Speaker 1: millions of years. There are more than five hundred different
Speaker 1: kinds with appetites, ranging from single celled organisms to insects
Speaker 1: to spiders. Today, let's talk about one of the most famous,
Speaker 1: the venus flytrap. The venus flytrap grows roots, stems, leaves, flowers,
Speaker 1: and seeds just like most plants, but it also grows
Speaker 1: two specialized lobes on the end of each leaf that
Speaker 1: form a hinged trap. Those lobes are distinctively green on
Speaker 1: the outside and reddish pink on the inside, with small
Speaker 1: bristles along the edges. But when they're open, they look
Speaker 1: like toothy little mouths calling for a snap. And when
Speaker 1: an insect or a racknid crawls across that pinkish inner surface,
Speaker 1: the trap slams shut and the plant digests its prey.
Speaker 1: It's a mouth and stomach in one. Although the venus
Speaker 1: flytrap has captivated people across the world. Wild populations of
Speaker 1: these plants actually grow in an incredibly small geographic area,
Speaker 1: a region along the coasts of North and South Carolina,
Speaker 1: only some seventy five square miles in area, that's about
Speaker 1: two hundred square kilometers. Their native areas are bogs and
Speaker 1: wetlands that are humid and sunny. They're so scarce that
Speaker 1: some early botanists doubted their existence despite all the stories
Speaker 1: spread about a flesh eating plant. But okay, if other
Speaker 1: plants can thrive on nothing but water, air, nutrients in
Speaker 1: the soil, and some sunshine, why do venus flytraps eat insects?
Speaker 1: Flytraps actually get a good deal of their sustenance just
Speaker 1: like other plants do. During photosynthesis, plants use the energy
Speaker 1: of the sun to drive a reaction that converts carbon
Speaker 1: dioxide and water into sugar and oxygen. The sugar produced
Speaker 1: is then converted to energy that the plant cells can
Speaker 1: use a molecule called adenosine triphosphate or ATP. ATP is
Speaker 1: what our cells used to get stuff done too. However,
Speaker 1: in addition to sugar, plants also need to make amino acids, vitamins,
Speaker 1: and other cellular components to survive in the coastal bogs
Speaker 1: where venus flytraps live, the soil is acidic and minerals
Speaker 1: and other nutrients are scarce. Most plants can't survive in
Speaker 1: this environment because they can't make enough of the building
Speaker 1: blocks necessary for growth. The venus flytrap evolved an alternate
Speaker 1: means of getting those key nutrients. Living creatures like insects
Speaker 1: provide a good source of the stuff that's missing from
Speaker 1: the soil, plus additional carbohydrates so that covers the y.
Speaker 1: But how do these plants catch and eat prey. A
Speaker 1: plant doesn't have a brain or even a nervous system
Speaker 1: to coordinate their functions and movements, nor do they have bones, tendons,
Speaker 1: and muscles to coordinate. But most plants do have some
Speaker 1: way of attracting animals or insects, regardless of whether they're
Speaker 1: going to eat them. Lots of flowering plants have evolved colors, scents,
Speaker 1: and sugary nectar to attract bees, butterflies, and other pollinators.
Speaker 1: In those cases, the animals get a snack, and they
Speaker 1: unwittingly ferry the plant's pollen to neighbors of the same species,
Speaker 1: thus fertilizing them. Hopefully. Similarly, fruits evolved to be sweet
Speaker 1: and tasty because if a bird or other animal eats
Speaker 1: them and later poops the seeds elsewhere unharmed, a new
Speaker 1: plant can grow. In the case of the venus flytrap,
Speaker 1: the inner surface of those specialized lobes secretes a sweet
Speaker 1: nectar that draws in insects searching for food. But the
Speaker 1: inner surfaces of the lobes also sport short, stiff, hair
Speaker 1: like structures that serve as a sort of motion to
Speaker 1: When a creepy crawley crawls across the surface and brushes
Speaker 1: two hairs in close succession or one twice, the lobes
Speaker 1: close down in as little as half a second, trapping
Speaker 1: the creature inside a fun fact or black thereof No
Speaker 1: one knows exactly how this works, ever since Charles Darwin
Speaker 1: described the species in eighteen seventy five, and he called
Speaker 1: it the most wonderful plant by the way. Ever since then,
Speaker 1: researchers have been trying to get to the bottom of
Speaker 1: this trapping mechanism, but it's difficult to observe what's going
Speaker 1: on inside a living plant during half a second of action.
Speaker 1: The prevailing hypothesis goes that a venus fly trap accomplishes
Speaker 1: this feat by rapidly changing the geometry of those specialized
Speaker 1: lobes via water transfer within the lobes upon stimulus. Let
Speaker 1: me break that down, Okay. Each lobe or half of
Speaker 1: a venus flytrap's trap seems to have two functional layers inside,
Speaker 1: an upper layer up against the pinkish interior surface of
Speaker 1: the trap and a lower layer up against the green
Speaker 1: outer surface of the trap. Cells within the layers contain water.
Speaker 1: That's not unusual. Cells generally do contain water, but the
Speaker 1: upper and lower layers are each capable of holding onto
Speaker 1: water and of transferring it quickly to each other. When
Speaker 1: the trap is open. That's actually a tense state for
Speaker 1: the lobes of the leaf, wherein more water is being
Speaker 1: held by the upper interior layer of cells. This makes
Speaker 1: each lobes slightly convex and holds the trap open. But
Speaker 1: when something triggers those motion detector hairs that somehow tells
Speaker 1: the plant to open up pores between the upper and
Speaker 1: lower layers, water quickly moves into the lower outer layer,
Speaker 1: making each lobes lightly concave, curling in around its prey.
Speaker 1: In a fraction of a second, this closed state is
Speaker 1: relaxed for the lobes of the leaf. They open back
Speaker 1: up again by slowly transferring water back to the upper
Speaker 1: interior layer, but it takes a while. Again, no one
Speaker 1: entirely understands how all this works, though there is some
Speaker 1: interesting research into all the biochemical details. But for our
Speaker 1: purposes today, let's focus in on what happens when that
Speaker 1: trap does close on some tasty prey. The lobes of
Speaker 1: the leaf form an airtight seal so that digestive fluids
Speaker 1: and insect parts are kept inside the trap, and so
Speaker 1: that bacteria and molds can't get in. Those toothy looking
Speaker 1: spines on the outer edges of the trap laced together
Speaker 1: and latch the trap shut. There is an upper limit
Speaker 1: to the size of insect that a trap can accommodate.
Speaker 1: The traps will grow up to around an inch long
Speaker 1: or about two and a half centimeters, and in order
Speaker 1: to close tightly, an insect that catches can only be
Speaker 1: about a third of that size. If an insect is
Speaker 1: too large, the trap can't form a seal against microbes,
Speaker 1: which will move in and eat the decomposing insect and
Speaker 1: the trap itself too. The trap will turn black and
Speaker 1: drop off of the plant, but back to dinner. Once
Speaker 1: an insect or a rapnet is firmly ensconced in the trap,
Speaker 1: the process of digestion can begin. The trap now serves
Speaker 1: as a miniature stomach, just like our stomachs. The trap
Speaker 1: secrete acidic digestive juices that do three things. They dissolve
Speaker 1: the soft tissues and sell membranes of the food. They
Speaker 1: serve as an antiseptic to kill any microbes that got
Speaker 1: in with the food, and they break down various proteins
Speaker 1: and other molecules into small pieces that the plant can
Speaker 1: take in. It takes some five to twelve days for
Speaker 1: a trapped digest prey, depending on the size of the prey,
Speaker 1: the age of the trap, and the ambient temperature. Older
Speaker 1: traps and colder temperatures make digestions slower. The process continues
Speaker 1: until all that's left of the insect is its herd
Speaker 1: exoskeleton and its bath of digestive juices. The plant reabsorbs
Speaker 1: the fluids and the trap slowly reopens, after which the
Speaker 1: praise remains are usually either washed away in the rain
Speaker 1: or blown away by the wind. A venus fly trap
Speaker 1: can tell the difference between living prey and a dead
Speaker 1: exoskeleton or other non edible debris that might fall in.
Speaker 1: Inanimate objects that trigger the trap's motion sensitive hairs won't
Speaker 1: keep moving once it slams shut. If there's no further
Speaker 1: stimulation of the hairs, the trap won't seal up, but
Speaker 1: it will be stuck in partially shut state until tension
Speaker 1: can be re established in the lobes of the trap.
Speaker 1: This process takes about twelve hours, at which point the
Speaker 1: unwonted object falls out. This selection process is pretty good,
Speaker 1: but not perfect. While the trap is out of commission,
Speaker 1: real food may be crawling all around the plant. Imagine
Speaker 1: if you had to sit with a chicken bone or
Speaker 1: peach pit in your mouth for twelve hours while the
Speaker 1: rest of your dinner sat on the table in front
Speaker 1: of you. Of course, the venus fly trap doesn't feel
Speaker 1: any kind of way about it. It's a passive participant
Speaker 1: in the process of eating dinner. Any given trap won't
Speaker 1: last the full lifetime of the plant. After about ten
Speaker 1: to twelve closures, either partial or complete, the trap will
Speaker 1: stop trapping and remain partially open. It'll devote its remaining
Speaker 1: time to photosynthesis, usually for around two to three months,
Speaker 1: while our imaginations dream up people eating killer plants. In reality,
Speaker 1: we're the threat to venus fly traps and other carnivorous
Speaker 1: plants in the wild. Venus fly traps today only cover
Speaker 1: about a third of their historic range. In the nineteen seventies,
Speaker 1: there were around four million of them. That's down to
Speaker 1: just over three hundred thousand as of twenty twenty due
Speaker 1: to over collection by humans and the draining and destruction
Speaker 1: of the natural wetlands where they grow. There's a hefty
Speaker 1: fine North Carolina felony charge for removing them from the wild,
Speaker 1: but lots of reputable plant nurseres propagate and sell them legally.
Speaker 1: If you grow one at home, you'll be looking to
Speaker 1: replicate its boggy, bright homeland with specialized soil and humid conditions.
Speaker 1: A terrarium can help. Check growing guides online or talk
Speaker 1: to your local garden center. A venus flytrap will grow
Speaker 1: to about five inches or thirteen centimeters tall, with about
Speaker 1: four to eight traps per plant. You'll want to provide
Speaker 1: it with two or three small flying insects like a
Speaker 1: house fly every month. A far cry from the feed
Speaker 1: me seemore eating habits of carnivorous plants in science fiction.
Speaker 1: Today's episode is based on the article how Venus flytraps
Speaker 1: work on HowStuffWorks dot Com, written by Anne Mieker O'Connell.
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