
Why These Bugs Live Inside Plants That Eat Them
Season 2 Episode 5 | 8m 22sVideo has Closed Captions
In Florida’s wetlands the carnivorous pitcher plant is blurring the lines between predator and ally.
In Florida’s wetlands, the carnivorous pitcher plant is blurring the lines between predator and ally. Home to entire unique ecosystems, there are more to these ancient organisms than many realize. So why do these beautiful and vicious plants have mercy on some and not others?
Problems playing video? | Closed Captioning Feedback
Problems playing video? | Closed Captioning Feedback

Why These Bugs Live Inside Plants That Eat Them
Season 2 Episode 5 | 8m 22sVideo has Closed Captions
In Florida’s wetlands, the carnivorous pitcher plant is blurring the lines between predator and ally. Home to entire unique ecosystems, there are more to these ancient organisms than many realize. So why do these beautiful and vicious plants have mercy on some and not others?
Problems playing video? | Closed Captioning Feedback
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Learn Moreabout PBS online sponsorshipI love pitcher plants because of their beauty.
The sarracenia pitcher plants are the most complex and amazing carnivorous plant.
The way that they operate and have digestive enzymes and attract the pollinators and their food to the plant- it's very clever.
They turn the tables on insects.
Think about this leaf, this pitcher, it's actually a death trap, for almost anything that would enter it.
But one of the things that makes pitcher plants so fascinating is that there is a certain set of organisms that actually circumvent the death trap, and they instead live within pitchers.
The pitcher, a prolific carnivorous plant, is blurring the lines between predator and ally.
Why do these beautiful and vicious plants have mercy on some and not others?
This area, Blackwater in northwest Florida, is one of the most diverse botanical areas in the United States.
What also draws me in and makes my love affair with pitcher plants even more enduring are the symbiosis.
The mystery of what are these organisms?
How do they interact with the plants?
How do they survive?
The pitcher plants are in flower right now and that is, quite spectacular.
And they're only in flower in the spring.
And this is, this is a picture plant right here.
I'm looking for insects..
Here's one right here that- the sepals are drying up.
You see them right here?
This is sarracenia leucophylla, known as the white top pitcher plants.
And we're looking inside of the pitcher and seeing insects that are stuck in there.
All carnivorous plants have four things in common: attracting prey, capturing prey, digesting prey, and then finally absorbing nutrients from the prey.
Prey items within pitcher plants are quite diverse and they range from mostly insects, but they also range through spiders and slugs and other crawling invertebrates.
Virtually any organism that's small and gets within a pitcher plant is doomed.
But there's a really interesting set of exceptions to that.
Why be symbiotic?
Well, it appears that that mass of decomposing prey, because it's around for a while within the pitcher, that abundance of decomposing organic matter, along with the abundant bacteria that feed upon that mass, those provide opportunities.
That's actually very energy rich for any organism that can capitalize on it.
There's a food web inside this pitcher.
Once a death trap, now a micro ecosystem.
And the decomposing prey is the base of the food chain.
Some of these symbionts are what we call obligate symbiotic.
They live nowhere else but the interiors of pitcher plants.
There is an entire genus of mites that lives only within the pitchers of the Western Hemisphere pitcher plants.
And it's present in every species of pitcher plant that we've checked so far.
So we have living sarraceniopus mites from within a pitcher that I removed when we were in the Nolan greenhouses.
And you can sense, as I focus on this, the mite is moving and it's moving very, very slowly through the prey remains.
Another group of interesting symbionts in sarracenia pitcher plants are the sarcophagi flies.
And what these do as larvae, they're living within the plants and they're eating the prey soon after it's captured.
We also get a midge.
Another aquatic insect is a larva.
And researchers documented that when these insect larvae are present, moving through the prey remains, the levels of nutrients like nitrogen are elevated relative to when the symbiotic larvae are absent.
One of the great questions is what effect do the symbionts have on the plants?
If any?
In most cases it's not yet been studied, but in a couple of cases, biologists did study the effects of the aquatic midge and the mosquito larvae.
And they found that these symbionts are beneficial to the plants by decomposing the prey more rapidly.
So they concluded that these symbionts are actually mutualists.
Mutualists are members of a symbiosis in which each half - the symbiont and the host benefit.
Not all symbionts are beneficial.
So the caterpillars of these Exyra moths get inside the pitchers.
They eat the interior tissues of the pitchers, and in the process, they've destroyed the pitcher.
It's actually a parasite.
And this one over here, this is a typical of the moth.
It eats, it starts in the larva, it starts eating the pitcher.
From the inside out.
You can think of the mutualist as having a buddy, your best friend.
You help each other.
Your friend is there in times of need, on the other hand, there are these moth larvae, the caterpillars that get in there and destroy.
So that would be a false friend.
somebody that when you first met, you thought it was a friend.
but it ends up you want to be done with that person.
A lot of people think that because pitcher plants are popular and beautiful, that virtually everything is known about them.
But that is far from the truth.
As biologists learn more and more, we began to realize that it's quite likely that the symbionts themselves are playing a major role in decomposition and digestion.
You can imagine experiments, in which, we have pitchers grown in a sterile environment with no symbionts and those with symbionts, and learning about the possible benefits.
But we have yet to solve those mysteries.
We do not know.
That work remains to be completed.
Pitcher plants, all of them are rare.
And unfortunately many of them are, threatened or endangered, outright endangered in terms of their long term survival.
Yet it's not just the pitcher, that we're losing, not just the plant species.
It's actually an entire community that lives within that pitcher.
Many species are utterly dependent upon that plant.
So it's absolutely essential that we continue with this work, and we document the life that's found inside a pitcher plant.
Our work of answering the most fundamental questions of how many species live within a pitcher plant.
What are these species?
Where do they occur?
These questions are absolutely critical to working out the future of pitcher plant biology.
I hope that for the future of pitcher plants that they will survive and that enough people would care about them to protect their habitats.
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