Nepenthes: Time to Eat

Summary: Do plants eat meat? Yes they do! Join Kiersten as she discusses the diet of Nepenthes which includes more than just meat.

 

For my hearing impaired listeners, a complete transcript of this podcast follows the show notes on Podbean

 

Show Notes:

“Caught in a Trap,” The Biologist 62(2) p12-14.

“Nepenthes lowii: the carnivorous plant that evolved into a toilet,” by Paul Simons. The Guardian, April 2023. https://www.theguardian.com

“Bats Are Acoustically Attracted to Mutualistic Carnivorous Plants,” by Michael G. Schoner, Caroline R Schoner, Ralph Simon, T. Ulmar Grafe, Sebastian J. Puechmaille, Liaw Lin Ji, Gerald Kerth. Current Biology, Volume 25, Issue 14, 20 July 2015, Pgs 1911-1916. https://doi.org/10.1016/j.cub.2015.05.054

Music written and performed by Katherine Camp

 

Transcript

(Piano music plays)

Kiersten - This is Ten Things I Like About…a ten minute, ten episode podcast about unknown or misunderstood wildlife.

(Piano music stops)

Welcome to Ten Things I Like About… I’m Kiersten, your host, and this is a podcast about misunderstood or unknown creatures in nature. Some we’ll find right out side our doors and some are continents away but all are fascinating. 

This podcast will focus ten, ten minute episodes on different animals and their amazing characteristics. Please join me on this extraordinary journey, you won’t regret it.

The fourth thing I like about Nepenthes is its diet. These are not your typical plants. Sunlight is not the only thing on the menu.

I have spoken of a portion of the diet in the previous episodes, so we all know that Nepenthes eats meat. But before we jump into that portion of their diet let’s look at the other half of their diet. It’s this half that led to the need for the meat eating side of Nepenthes nutrition.

Nepenthes is like other plants that use photosynthesis to grow. I don’t know about all of you listeners, but it has been a minute since 6th grade science class, so here is a refresher on how photosynthesis works. 

Photosynthesis is the process by which plants use sunlight, water, and carbon dioxide to create sugars that they can utilize to survive. Plants take in carbon dioxide through small holes in the leaves, stems, flowers, and other parts of the plant. They will combine that with water, usually absorbed through the roots, and sunlight. The sunlight is the energy that helps the plant combine the carbon dioxide and the water together to create glucose which they use as food to grow big and strong.

If they only need those three things, what’s up with the soil? Soil offers plants minerals that they need to boost their health and growth.  Plants can live without it but to reproduce successfully they need an extra kick. The need for this extra kick is why Nepenthes evolved to eat meat. 

Most Nepenthes species grow in nutrient poor soil or no soil at all. So they evolved to get the extra minerals they need from another source. 

How do you catch prey if you don’t have teeth or claws and you are rooted in place? Well, you bring the prey to you! Nepenthes developed pitcher traps to attract and catch prey without having to use teeth and claws or roam about searching for prey. The pitcher develops from tendrils that grow as the plant matures. Tendrils will emerge from the midline of leaves and as it matures the tip of the tendril will begin to inflate with air. Once it has inflated to the desired size, which depends on the species and whether it is a lower pitcher or an aerial pitcher, it will fill with liquid. The top of the pitcher will pop open when the pitcher is ready for use. 

The pitchers of Nepenthes are classified as pitfall traps. This means that they are relying on insects falling into the pitcher and getting stuck inside. A pitfall trap is a trap that something falls into and cannot climb the walls to get out. So, how does this work for the Nepenthes pitcher?

The pitcher will attract insects with the scent of pollen. Insects will investigate the trap searching for the source of the smell. There is no pollen to be found inside the pitcher so the insects will turn to leave and discover that they cannot. As they try to climb out, the waxy lining of the pitcher will flake away leaving the insect struggling to get out. But no upward motion is possible and the prey item eventually falls into the liquid at the bottom of the pitcher.

The liquid is mainly water until prey falls in and sloshes the water around as it attempts to get out. The vibrations created by the struggle stimulate digestive glands which release a digestive acid. The acid is so strong that an insect the size of a midge will disappear completely within hours. Nepenthes rajah, one of the largest Nepenthes species, can digest mice!

What are they getting from these digested insects and mammals? Nitrogen and phosphorus which are vital minerals for the healthy growth of the plant. Those of you that are gardeners probably recognize those elements as being important to plant survival. If you supplement your gardens with fertilizer the amount of nitrogen and phosphorus are extremely important. 

Let’s take a closer look at a specific Nepenthes species’s hunting strategy. Nepenthes rafflesiana produces two different pitchers, upper and lower, like many pitches plants do. The uppers pitchers specialize in attracting flying insects while the lower pitchers focus on terrestrial insects.

The upper pitchers are narrow and release fragrant compounds that mimic the scent of flowers. This attracts a wide range of rainforest pollinators that mistake the scent for a good snack. They will enter the pitcher in search of the source of the aroma and come in contact with sticky polysaccharides that coat the wings rendering them useless. The insects can’t fly out and fall into the liquid to be digested.

The lower pitchers of Nepenthes rafflesiana use a lining of wax crystals to trap terrestrial insects. It attracts mainly ants. When the ants enter the pitcher the wax crystals attach to the ant’s feet preventing them from climbing out of the pitcher. It clings to the feet causing them to slip along the surface of the pitcher leading them to the liquid death below.

Some Nepenthes are generalists and are happy to take whatever they can get in their traps, but remember competition for pollinators is fierce so some spices have become specialists. Nepenthes albomarginata has a band of white hairs just below the rim of its pitchers. These hairs are bait for termites. And this Nepenthes sure knows how to do it right. It can catch 20 termites per minute during a frenzied feast.

Okay, now we’re going to talk about what inspired me to report on Nepenthes for my podcast. Remember in the first episode when I said these plants fed on something unusual that gives a whole new twist on the term “potty mouth”? Well, here we go!

Nepenthes rajah can digest mice and rats, but that’s not what it’s really shooting for when it attracts these animals. What is really wants is the rodents poop. Yep, that’s right it wants the rodent to use its pitcher as a potty. The feces of these animals is high in nitrogen  and much easier to digest than the body of an insect or mammal. 

Nepenthes lowii was the species that caught my eye when I was researching unusual plants. This plant has large pitchers that have evolved to attract mountain tree shrews that slip into the pitcher to lick a fatty substance that oozes from the lip of the pitcher. The shrew balance on the edge of the pitcher and as they eat they leave behind a deposit. There is some speculation that the substance emitted by the pitcher my have a laxative component that ensures the animal leaves behind a deposit before the depart. 

Nepenthes hemsleyana attracts a specific animal to roost in its pitchers so it can collect poo all day long. The lid of this plant’s pitcher is shaped specifically to reflect bat echolocation frequencies. Bats such as Hardwicke’s Wooly Bat use echolocation to find acceptable day roosts. They search for the right reflection from a plant structure to indicate an acceptable daytime roost. Nepenthes hemsleyana had evolved to reflect the correct frequency luring the bat in to roost throughout the day. The bat will poop as they sleep the day away and the plant will catch it in the pitcher. Talk about a Bed and Breakfast!

Can you believe it! This plant is so amazing!! I can go on about Nepenthes diets, but I’ve run over time already. I’m so glad you joined me for this episode of Nepenthes because my fourth favorite thing, honestly my most favorite thing, about them is their diet.

If you're enjoying this podcast please recommend me to friends and family and take a moment to give me a rating on whatever platform your listening. It will help me reach more listeners and give the animals I talk about an even better chance at change. 

Join me next week for another episode about Nepenthes.    

 

(Piano Music plays) 

This has been an episode of Ten Things I like About with Kiersten and Company. Original music written and performed by Katherine Camp, piano extraordinaire.