Spot on Science: Hungry Hungry Plants?!
Margaret learns about three carnivorous plants in Ohio: the Pitcher Plant, Roundleaf Sundew, and Bladderwort. Each has a unique trap mechanism that lets absorbed needed nutrients from their insect prey.
Class Discussion Questions:
1) Create a Venn Diagram comparing decomposers, producers, and consumers.
2) How are food chains and food webs similar? How are they different?
3) What special adaptations do carnivorous plants have that allow them to thrive in their unique ecosystems?
Read the Script:
[Margaret] When it comes to food chains and food webs, we're used to thinking about just three types of organisms, producers, like plants that use the sun, water, soil, and air to grow, then there are consumers, you, me, and the animals that chow down on the producers, and, of course, decomposers, mushrooms, fungus, things that break down producers and consumers after they die. But some organisms don't fit neatly into one category. I'm talking about carnivorous plants. Not only are they producers, but they are also consumers. It's pretty crazy. And, surprising to me, is that we have them right here in Ohio. To find out more about these hungry plants, I met up with Adam Wohlever from the Ohio Department of Natural Resources at a bog in Kent.
[Adam] So, a carnivorous plant is a plant that has adapted to get the nutrients that it needs from other sources, mainly by eating insects. So, a carnivorous plant, while it does do some photosynthesis to get the energy it needs, the soils here are really poor in nutrients, so it eats the insects and it's able to digest them and get the amino acids and the nitrogen that it can't get out of the soil through those insects.
[Margaret] So, while normal plants are able to get everything they need from the environment, these fellows need to make up for a lack of nutrients. I know what you're wondering. Carnivorous plants, do they eat animals? Could they eat me?
- Feed me!
[Adam] In Ohio, they don't typically eat animals, but there are hundreds, if not thousands, of species of carnivorous plants throughout the world. Some of them are so big that they've been known to eat lizards, rats, small mammals, but we won't see any of that here.
[Margaret] Okay. Now that I know it's safe to get up close with these plants, let's look at the three species found at the Triangle Lake Bog State Nature Preserve. We've got the northern pitcher plant, the roundleaf sundew, that one sounds nice, and the bladderwort. Uh, ew. They each have a specific way of luring insects to snack on.
[Adam] A pitcher plant has what we call a pitfall trap so that the pitcher, okay, or the container itself, is a modified leaf, and it's got all sorts of little colors and venation on it, and sometimes it secretes a bit of a nectar, and this attracts the insect. The insect lands on this pitcher leaf, and it begins to crawl around. Well, eventually, as it crawls around, it comes to a point on the leaf where it's really slippery and it can't get any traction, and it falls down into this trap, and it starts to break down and become digested over time through enzymes and bacteria, and it's absorbed and converted into amino acids that the plant can use, so that's kind of the process that takes place.
Some of the other plants that are out here, like the roundleaf sundew, this is really similar to like, the venus fly trap, which people are really familiar with. It uses a flypaper trap. So, it has this kind of open leaf, and it has all these little glands and secrete nectar, and that attracts the insect, but once they land, they become stuck, and this leaf begins to kind of close around the insect and, almost like a stomach, and digests it that way. But that movement of that leaf moving expends a tremendous amount of energy, so it has to really be successful in capturing insects so it can survive.
The third one that we have here, the bladderwort, it has a bladder-type trap. So, underneath the surface of the water is where all the action takes place, and there's these tiny little sacks or bladders, and they're negatively pressurized. They've got these little trigger kind of guard hairs on the bladder. So, what happens is a small, almost microscopic organism called zooplankton, when it comes close to these bladders, it opens up, like, in the blink of an eye, it just sucks all the water and all the insect in really quickly, and digests it through that process. So, there's all these different kinds of traps, all these different kinds of mechanisms that have to be working for each one of these plants to be successful and survive.
[Margaret] Wow. Lots of patience and work to catch and digest such a tiny meal, but carnivorous plants are more than just fascinating.
[Adam] I mean, carnivorous plants are very important to the ecosystem. One, they control insects, right? So, a lot of people think, "Wow, this must be great for mosquito control." While that's somewhat true, it's actually beneficial for mosquitoes, in some aspects. There's actually a species of mosquito that carries out its life cycle inside the pitcher of the northern pitcher plant, which is a carnivorous plant. So the plant itself is beneficial to the life cycle and the life processes of certain insects, as well as eating them for its own purposes, so it's kind of in an interesting relationship.
[Margaret] We're lucky to have so many species of carnivorous plants here in Ohio. They can teach us about absorbing nutrients and adapting to survive in difficult situations. Some scientists are even studying the plants to find new ways to make super slippery surfaces and to reduce the mosquito population. But we play a big role in making sure the hungry plants are able to stick around. Adam says that the plants and their habitats are rare. Many species of carnivorous plants are threatened or even endangered, so it's up to us to protect their natural habitats.