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Most plants use colorful flowers to attract their favorite pollinators. But Marcgravia evenia is trying to attract bats, so it needs to do things a little differently, leading to some unique-shaped leaves.

Hosted by: Hank Green

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Sources:
https://www.science.org/doi/abs/10.1126/science.1204210
https://www.sciencedirect.com/science/article/abs/pii/S1369526616300942
https://www.sciencedaily.com/releases/2011/07/110728144717.htm
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0136657

Images:
https://www.storyblocks.com/video/stock/green-oak-leaves-against-bright-sun-cu-rqbdfuwiwj7upq4ni
https://www.storyblocks.com/video/stock/aerial-view-of-fields-full-of-sunflowers-for-oil-production-near-leon-in-spain-nature-agriculture-in-spanish-countryside-landscape-natural-beauty-seen-from-drone-flying-in-sky-r647qvghsjztklmwk
https://www.eurekalert.org/multimedia/592463
https://www.eurekalert.org/multimedia/667926
https://www.eurekalert.org/multimedia/561153
https://www.eurekalert.org/multimedia/751177
https://commons.wikimedia.org/wiki/File:Bat_echolocation.jpg
https://www.eurekalert.org/multimedia/771141
https://www.inaturalist.org/observations/68695436
https://www.eurekalert.org/multimedia/771141
https://www.istockphoto.com/photo/the-background-image-that-is-green-the-colors-of-the-autumn-leaves-are-perfect-gm1320109003-406772585
https://www.eurekalert.org/multimedia/631651
https://www.eurekalert.org/multimedia/763523
[♪ INTRO].

Plants don’t ask for a whole lot. They just want a little sunshine, maybe some  water, and a way to spread their genes around.

And most plants have figured  out how to fill that final need the same way: with colorful  flowers that attract pollinators. But Marcgravia evenia does  things a little differently because its favorite pollinator is a bat. And though bats do rely on  vision in certain situations, they don’t use it much while foraging at night.

So M. evenia has found another way  to attract them: by reflecting sound. M. evenia is a flowering  vine that’s endemic to Cuba. And It’s mainly pollinated by nectar-feeding bats, which works great if those  bats can find the plant.

So this vine evolved a pretty clever adaptation. It has disc-shaped leaves  that act like satellite dishes similar to what you might use to get a TV signal. Bats can find these plants in the dark  using echolocation, where they make a sound to distinguish or find something with  its echo that bounces back to them.

Bats produce echolocation sounds  with their voice boxes or, in some species, by clicking their tongues. When these sounds bounce off of  things, like the disc-shaped leaves, it changes the frequency of the sound. And the bats can detect  this slight change in sound with specialized receptor cells in their ears.

And these tiny changes are vital for the bat. With them, bats can tell  how fast things are moving, which way they're going, and  ultimately where to find food. So, bats can use echolocation to find M. evenia  a lot faster than they can to find other plants.

Because when bats send out a sound, the leaves return echoes that  are very distinct to that plant. And because of their form, the sound can be  amplified in a bunch of different directions. The leaf’s center and edge both reflect sound  differently, but in a way that overlaps.

When sound is reflected off  leaves that are more flat, they produce a bunch more background  noise compared to the M. evenia leaves. Researchers were curious about how  effective these vine leaves were, so they trained some bats to drink  from feeders in a lab setting. Then, they presented the bats  with three different scenarios.

In one, the feeder was on its own; in the next, it was surrounded by some typical-looking leaves. And in the last one, the feeder  was surrounded by artificial leaves shaped like the leaves from M. evenia. Researchers found that the bats  could find the feeder twice as fast when hidden in the artificial M. evenia leaves.

But it does come with a small price. Flat leaves usually are much more  efficient at absorbing sunlight because of all the exposed area. Disc-shaped leaves, on the other hand,  aren’t as good at photosynthesis, because their curved shape doesn't leave  as much surface exposed to the sunlight.

This seems like a problem for the plant  because they produce fewer nutrients than when they had a flat leaf, but it  might actually be a pretty fair trade. Because these plants are so scarce,  they need efficient pollinators, and bats also need a lot of food to  keep up with all that flying around. So researchers hypothesize that  these plants evolved these leaves over flashy flowers to have less  competition when it comes to pollinators.

Which is a great example of how  everything in nature has its trade-offs, but some things are just worth a little sacrifice. Thanks for watching this episode of SciShow! We have made thousands of  educational videos over the years, and we’ve been able to offer them for  free because of our patrons on Patreon.

It’s the end of the year. I’ve just been  going over our budgets here at Complexly, and I know this to be a true fact. So, to all of our patrons, thank you  for what you do to make SciShow happen.

If you’re not a patron and you want  to learn more about what that means, you can go to Patreon.com/SciShow. [♪ OUTRO].