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Poop-Like Plant Tricks Dung Beetles Into Burying Its Seeds

Nature may abhor a vacuum, but she certainly rewards a liar. Wild cheaters abound in the plant and animal kingdoms, from the tippy-top of the food chain to the very bottom. The newest addition to the rogues gallery is Ceratocaryum argenteum, a South African plant that quite literally looks like crap. 

Scientists found that C. argenteum’s seeds are so convincingly poop-like that dung beetles will make off with them and bury them in the dirt. The large, round seeds not only look like the dung of local antelopes—they also smell like it, which is how they can trick dung beetles into planting them.

Poop is, unsurprisingly, the center of the dung beetle’s universe. Food, drink, a place to raise the kids, and sometimes even home are rolled into one smelly ball. As such, dung beetles can be a little single-minded, which makes them a prime target for tricksters and scammers. Burrowing owls, for example, casually strew balls of dung outside their dens, then gobble up any beetles that come sniffing around.

In a paper published this week in Nature Plants, researchers from the University of South Africa and University of KwaZulu-Natal analyzed the stink emanating from C. argenteum seeds. They found that a number of the seeds' smelly compounds matched those in antelope poop precisely.

To find out if the seeds’ odor actually appealed to dung beetles, the scientists scattered 195 C. argenteum seeds in areas of heavy dung beetle traffic. They set up motion-capture cameras at each site and attached fluorescent threads to each seed to make it easy to spot if a beetle carried it off. Sure enough, within 24 hours, dung beetles had absconded with and buried more than one quarter of the reeking seeds. The stench also seemed to deter animals that might eat the seeds without burying them.

Once buried, the C. argenteum seeds sprout and start a whole new generation of smelly, lying plants. Burial keeps the seeds safe from any chaos on the surface, which is a big deal in the fire-prone shrublands where they make their home.

It’s a pretty neat trick, but how did the plants come up with it? Lead author Jeremy Midgley suspects a combination of dumb luck and chemical evolution.

“I guess that a mutant individual, which had some chemical on the seed coat, attracted the odd beetle and the seed was buried," Midgley said in an interview with Discovery News. "This plant then did very well because fewer seeds were discovered and eaten by small mammals, and that fires damaged fewer of the buried seeds."

Meanwhile, the beetles who did the heavy lifting in this particular experiment were left looking pretty silly. At least they weren't forced to wear tiny cardboard hats. 

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Big Questions
What Are Those Tiny Spots on Apples?
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The little pinprick spots on apples, pears, and potatoes are called lenticels (LEN-tih-sells), and they’re very important.

Plants need a constant stream of fresh air, just like people, and that “fresh air” means carbon dioxide. Flowers, trees, and fruit all take in carbon dioxide and give off oxygen. But unlike people, plants don’t have nostrils.

That's where a plant's lenticels come in. Each little speck is an opening in the fruit or tuber’s skin or the tree’s bark. Carbon dioxide goes in, and oxygen comes out. Through these minuscule snorkels, a plant is able to “breathe.”

Like any opening, lenticels are vulnerable to infection and sickness. In an apple disease called lenticel breakdown, a nutrient deficiency causes the apples’ spots to darken and turn into brown pits. This doesn’t hurt the inside of the fruit, but it does make the apple look pretty unattractive. In the equally appealing “lenticel blotch pit,” the skin around the apple’s lenticels gets patchy and dark, like a weird rash. 

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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History
Read One of the First Eyewitness Accounts of Antarctica
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Stupendous icebergs, live volcanoes, and delicious (if slightly too rich) penguin soup—just a few of the details recorded on one of the earliest eyewitness accounts of Antarctica. Written in the 1840s by the botanist Joseph Dalton Hooker, the Antarctic Journal introduced the southern continent's natural wonders to the world. Now, the Joseph Hooker Correspondence Project and the Biodiversity Heritage Library have preserved and digitized it for a new generation of exploration junkies.

Born 200 years ago in Suffolk, England, Hooker would become one of the greatest naturalists and explorers of the 19th century. He was a close friend of Charles Darwin and was director of the Royal Botanic Gardens, Kew from 1865 to 1885. But before that, at just 22 years old, he embarked on an epic voyage of discovery to Antarctica.

Chalk portrait of Joseph Dalton Hooker by George Richmond, 1855
Chalk portrait of Joseph Dalton Hooker by George Richmond, 1855
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Hooker served as the assistant surgeon and botanist on the adventure under the command of Captain James Clark Ross, a veteran of seven previous Arctic expeditions. Like all of the Royal Navy’s voyages of discovery at the time, this one had specific orders: confirm the existence of the southern continent, find the south magnetic pole, collect flora and fauna, and chart new geographic features.

Armed with 25 reams of paper for preserving plants, glass greenhouses for live specimens, natural history books, and microscopes—plus a trunk of polar clothing—Hooker set up his tiny field laboratory in the HMS Erebus, the larger of the expedition’s two vessels.

The Erebus and the HMS Terror left England at the end of September 1839 and arrived in Hobart, Tasmania, in August 1840. From there, they sailed south and soon were in view of a rocky land ringed with pack ice and icebergs. Hooker recorded the incredible sights in his journal. "Saw a shoal of whales, and for the first time an iceberg, a most magnificent flat topped mass of ice about 160ft high, and a quarter of a mile long," he reported on December 28, 1840.

The ships skirted ice floes and inched closer to the continent. Mountains funneled massive glaciers toward the sea (which Ross named after himself), while a huge barrier of floating ice—later named the Ross Ice Shelf—created a perpendicular wall rising more than 160 feet above the ocean's surface, extending to the horizon. Hooker noticed rafts of penguins, white petrels, and gulls heading toward a hilly island at the northern end of the ice wall.

"At 8:45, observed the smaller hills on the Island … emitting small puffs of smoke, a discovery which interested us all very much," Hooker wrote on January 28, 1841. "4:30, observed the volcano emitting immense clouds of black smoke rising perhaps 300 feet above it; its margins tinged white by the sun, with a distinct red tinge from the fire below; it was a magnificent spectacle and a most extraordinary one."

The crew had discovered Antarctica's two largest volcanoes, which Ross named Mount Erebus and Mount Terror after their ships.

In addition to the southern continent, the expedition visited Australia, New Zealand, and smaller subantarctic islands. Whenever the ship anchored, Hooker went ashore to collect mosses, lichens, algae, and vascular plants. At sea, he deployed a tow net to capture plankton and other sea life. If the plants were frozen into the rocky soil, Hooker would chip them out of the earth and sit on them until they thawed. "The observations Hooker recorded in this [Antarctic Journal] and numerous other notebooks formed the basis of a flora of Antarctica and also of the wider regions visited," writes Cam Sharp Jones, the Joseph Hooker Correspondence Project officer at the Royal Botanical Gardens, in a blog post.

Botanical illustration in Joseph Dalton Hooker's 'Flora Antarctica'
Hooker's drawing of Nothofagus betuloides, the Magellan beech, which he collected on the Ross expedition.
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The most colorful passages in Hooker's journal recount the antics of the ubiquitous penguins, which provided the only fresh meat for the crew during the voyage. "At first we had a dozen on board running wild over the decks following a leader … until one day the leader, finding the hawse hole [a small hole in the ship's hull for cables to pass through] empty, immediately made his exit & was followed by the rest, each giving a valedictory croak as he made his escape," Hooker wrote.

Penguins that didn't escape were made into all manner of entrees. "Their flesh is black & very rich & was much relished at first for stews, pies, curries, etc.," Hooker mused. "After a day or two we found it too rich with a disagreeable flavour … except in the shape of soup, which is certainly the richest I ever ate, much more so than hare soup which it most resembles."

After four years in ice-strewn seas, the entire crew was surely sick of penguin soup and longing for home by the beginning of 1843. The Ross expedition returned to England on September 4, having achieved most of its goals. Ross inferred the position of the south magnetic pole, confirmed the existence and character of the southern continent, and charted huge stretches of its coastline. Hooker recorded plant and animal life that was entirely new to science, which he published in his six-volume Flora Antarctica, a catalogue of more than 3000 descriptions and 530 illustrations of plants species he found on the voyage. The Erebus and Terror were freshened up and put back into naval service on the doomed Franklin expedition in 1845.

To commemorate Hooker's roles in exploration and science (and to mark the bicentennial of his birth), the Royal Botanical Gardens, Kew is hosting an exhibition of his letters, paintings and prints from his travels, photographs, journals, important botanical illustrations, and even his own belongings. On display through September 17, 2017, Joseph Hooker: Putting Plants in Their Place demonstrates how, through exploration and curiosity, he transformed the study of plants into true science. In doing so, he brought us closer to one of Earth's most remote places.

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