Scientists Have Figured Out Why Marimo Balls Only Float During the Day

Shaunacy Ferro, Mental Floss
Shaunacy Ferro, Mental Floss

Scientists have solved a long-running mystery surrounding marimo, the fuzzy balls of green algae that Japan considers a national treasure.

Though marimo are known for nestling adorably at the bottom of rivers and lakes, they’re not always bottom dwellers. They sink at night, but during they day, they float—and until now, researchers weren’t quite sure why. As Atlas Obscura reports, a new study gets to the bottom of the mystery: It’s photosynthesis.

The study, published in Current Biology, finds that floating and sinking are natural byproducts of the marimo’s circadian rhythm driven by photosynthesis.

During the day, bubbles form within the spherical balls of Aegagropila linnaei algae, making them float to the surface of the water. In order to find out what drives the formation of these bubbles, researchers from the University of Bristol used a chemical that blocks photosynthesis. They found that bubbles didn’t form on chemically altered marimo, nor did the algae balls float, even when they were exposed to 48 hours of constant light.

Once they knew that photosynthesis was key to marimo buoyancy, the researchers exposed their lab-grown marimo to different light conditions in order to test whether their circadian rhythm plays a role in floating. The marimo were exposed to 12 hours of darkness and 12 hours of light during the day, then transferred to an environment with constant dim, red lighting for a few days. When the researchers then exposed these algae balls to bright light at the beginning of the day—mimicking the natural light cycle—they found that the marimo floated to the top of the water quicker than they did if they were exposed to bright light in the middle of the day. Basically, the marimo had jet lag.

The researchers suggest that this day-night buoyancy cycle might help the marimo maximize the amount of light they get each day. Since there’s less light at lower depths (like at the bottom of a lake), marimo float to the top of the water to maximize their potential for photosynthesis each day.

Marimo are endangered in the wild, and are no longer found in many of the lakes that were once teeming with the balls of algae. Given that photosynthesis drives the marimo’s daily cycle, these population changes could be due to pollution changing how much light penetrates the water in those lakes, according to Dora Cano-Ramirez, the study’s first author.

[h/t Atlas Obscura]

Does the Full Moon Really Make People Act Crazy?

iStock.com/voraorn
iStock.com/voraorn

Along with Mercury in retrograde, the full moon is a pretty popular scapegoat for bad luck and bizarre behavior. Encounter someone acting strangely? Blame it on the lunar phases! It's said that crime rates increase and emergency rooms are much busier during the full moon (though a 2004 study debunked this claim). Plus, there's that whole werewolf thing. Why would this be? The reasoning is that the Moon, which affects the ocean's tides, probably exerts a similar effect on us, because the human body is made mostly of water.

This belief that the Moon influences behavior is so widely held—reportedly, even 80 percent of nurses and 64 percent of doctors think it's true, according to a 1987 paper published in the Journal of Emergency Medicine [PDF]—that in 2012 a team of researchers at Université Laval's School of Psychology in Canada decided to find out if mental illness and the phases of the Moon are linked [PDF].

To test the theory, the researchers evaluated 771 patients who visited emergency rooms at two hospitals in Montreal between March 2005 and April 2008. The patients chosen complained of chest pains, which doctors could not determine a medical cause for the pains. Many of the patients suffered from panic attacks, anxiety and mood disorders, or suicidal thoughts.

When the researchers compared the time of the visits to the phases of the Moon, they found that there was no link between the incidence of psychological problems and the four lunar phases, with one exception—in the last lunar quarter, anxiety disorders were 32 percent less frequent. "This may be coincidental or due to factors we did not take into account," Dr. Geneviève Belleville, who directed the team of researchers, said. "But one thing is certain: we observed no full-moon or new-moon effect on psychological problems."

So rest easy (or maybe not): If people seem to act crazy during the full Moon, their behavior is likely pretty similar during the rest of the lunar cycle as well.

This story was updated in 2019.

NASA Reveals How Living in Space for a Year Affected Scott Kelly’s Poop

NASA, Getty Images
NASA, Getty Images

When you agree to be part of a yearlong space study, you forfeit some right to privacy. In astronaut Scott Kelly’s case, the changes his body endured while spending a year at the International Space Station (ISS) were carefully analyzed by NASA, then published in a scientific journal for all to see. Kelly submitted blood samples, saliva samples, and cheek swabs. Even his poop was subjected to scrutiny.

As PBS reports, Scott Kelly’s fecal samples revealed that his gut microbiome underwent significant but reversible changes during his time in orbit. In what was surely good news for both Kelly and NASA, his gut bacteria didn’t contain anything “alarming or scary,” according to geneticist Martha Hotz Vitaterna, and it returned to normal within six months of landing on Earth.

Even after being subjected to the challenging conditions of space, “Scott’s microbiome still looked like Scott’s microbiome, just with a space twist on it,” said Vitaterna, who was one of the study’s authors.

The fecal probe was one small part of a sweeping NASA study that was just published in the journal Science, more than three years after Kelly’s return. Dubbed the Twins Study, it hinged on the results of Kelly’s tests being compared with those of his identical twin, retired astronaut Mark Kelly, who remained on Earth as the control subject.

NASA’s goal was to gain insight into the hazards that astronauts could face on proposed long-term missions to the Moon and Mars. The agency has gone to great lengths to get this information, including offering to pay people $18,500 to stay in bed for two months in order to replicate the conditions of anti-gravity.

It also explains why NASA was willing to launch unmanned rockets into space to collect samples of Kelly’s poop. On four different occasions at the ISS, Kelly used cotton swabs to pick up poo particles. When the rockets arrived to drop off lab supplies, they returned to Earth with little tubes containing the swabs, which had to be frozen until all of the samples were collected. The process was tedious, and on one occasion, one of the SpaceX rockets exploded shortly after it launched in 2015.

The study also found that his telomeres, the caps at the ends of chromosomes, had lengthened in space, likely due to regular exercise and a proper diet, according to NASA. But when Kelly returned to Earth, they began to shorten and return to their pre-spaceflight length. Shorter telomeres have a correlation with aging and age-related diseases. “Although average telomere length, global gene expression, and microbiome changes returned to near preflight levels within six months after return to Earth, increased numbers of short telomeres were observed and expression of some genes was still disrupted,” researchers wrote.

Researchers say more studies will be needed before they send the first human to Mars. Check out NASA's video below to learn more about what they discovered.

[h/t PBS]

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