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Nick Hobgood via Wikimedia Commons // CC BY-SA 3.0

Coral and Algae Have Been Friends for 212 Million Years

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Nick Hobgood via Wikimedia Commons // CC BY-SA 3.0

Some classics were just made to go together. Peanut butter and chocolate. Thanksgiving dinner and stretch pants. Scleractinian corals and dinoflagellate algae. And boy, do those two go way back—scientists looking at fossils say the two have been cohabiting since at least about 212 million years ago, in the Late Triassic Period. The researchers published their report today in the journal Science Advances.

Happy, healthy coral is essential for a happy, healthy reef. To stay happy and healthy, many modern corals have forged super close relationships with teeny algae called zooxanthellae. The corals give the algae a safe place to live and the chemical components for photosynthesis, while the algae make oxygen, keep the water clean, and produce all kinds of helpful nutrients. The pair really have a good thing going.

But just how long it’s been going on has been anybody’s guess. Previous studies on the pair’s relationship have been largely speculative, using data from modern-day corals to imagine their ancestors’ world.

Now, two new scientific techniques, one visual and one chemical, have allowed us to get a far more accurate picture of coral history.

Earlier this year, lead author Katarzyna Frankowiak and a number of her co-authors reported that they’d figured out how to tell if a fossilized hard coral had been in a relationship with algae. The trick, they said, is to look very closely at the coral’s skeleton to see how it had grown and aged. Even when the algae itself was long gone, its presence had left irrevocable (if microscopic) changes in the coral’s life.

For the new study, the researchers applied this technique to tiny samples of fossilized hard corals found near the former Tethys Sea in Turkey. They used a variety of high-powered microscopes to examine the fossils in the most minute of detail and found that the skeletons of these ancient, ancient samples looked a lot like those of modern symbiotic hard corals.

Algae activity (brown dots in the tissue, upper left image) is recorded in the coral skeleton as structural (growth bands; upper right image) and geochemical signatures. Such regular growth bands occur in Upper Triassic (ca. 220 Ma) scleractinian corals (lower images) as well. Image Credit: Isabelle Domart-Coulon (upper left), Jarosław Stolarski (upper right, and lower images)

The second new method concerned the corals’ chemical composition. The experience of living with algae alters a coral’s very molecules, changing the ratio of various oxygen, carbon, and nitrogen isotopes. And just as with the visual inspection, analysis of the fossil corals’ isotopes suggested that they’d been sharing their lives with zooxanthellae.

Analyzing the coral isotopes yielded another insight: the sea in which these buddies lived was likely in pretty poor condition. The fossil corals shared a similar ratio of nitrogen isotopes with modern symbiotic Bermuda corals, which are currently struggling in nutrient-starved waters. It’s possible, the researchers say, that these difficult conditions were what inspired the algae and the corals to band together in the first place.

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Animals
Owning a Dog May Add Years to Your Life, Study Shows
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We've said that having a furry friend can reduce depression, promote better sleep, and encourage more exercise. Now, research has indicated that caring for a canine might actually extend your lifespan.

Previous studies have shown that dog owners have an innate sense of comfort and increased well-being. A new paper published in Scientific Reports and conducted by Uppsala University in Sweden looked at the health records of 3.4 million of the country's residents. These records typically include personal data like marital status and whether the individual owns a pet. Researchers got additional insight from a national dog registry providing ownership information. According to the study, those with a dog for a housemate were less likely to die from cardiovascular disease or any other cause during the study's 12-year duration.

The study included adults 40 to 80 years old, with a mean age of 57. Researchers found that dogs were a positive predictor in health, particularly among singles. Those who had one were 33 percent less likely to die early than those who did not. Authors didn't conclude the exact reason behind the correlation: It could be active people are more likely to own dogs, that dogs promoted more activity, or that psychological factors like lowered incidences of depression might bolster overall well-being. Either way, having a pooch in your life could mean living a longer one.

[h/t Bloomberg]

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Big Questions
Why Don't We Eat Turkey Tails?
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Turkey sandwiches. Turkey soup. Roasted turkey. This year, Americans will consume roughly 245 million birds, with 46 million being prepared and presented on Thanksgiving. What we don’t eat will be repurposed into leftovers.

But there’s one part of the turkey that virtually no family will have on their table: the tail.

Despite our country’s obsession with fattening, dissecting, and searing turkeys, we almost inevitably pass up the fat-infused rear portion. According to Michael Carolan, professor of sociology and associate dean for research at the College for Liberal Arts at Colorado State University, that may have something to do with how Americans have traditionally perceived turkeys. Consumption was rare prior to World War II. When the birds were readily available, there was no demand for the tail because it had never been offered in the first place.

"Tails did and do not fit into what has become our culinary fascination with white meat," Carolan tells Mental Floss. "But also from a marketing [and] processor standpoint, if the consumer was just going to throw the tail away, or will not miss it if it was omitted, [suppliers] saw an opportunity to make additional money."

Indeed, the fact that Americans didn't have a taste for tail didn't prevent the poultry industry from moving on. Tails were being routed to Pacific Island consumers in the 1950s. Rich in protein and fat—a turkey tail is really a gland that produces oil used for grooming—suppliers were able to make use of the unwanted portion. And once consumers were exposed to it, they couldn't get enough.

“By 2007,” according to Carolan, “the average Samoan was consuming more than 44 pounds of turkey tails every year.” Perhaps not coincidentally, Samoans also have alarmingly high obesity rates of 75 percent. In an effort to stave off contributing factors, importing tails to the Islands was banned from 2007 until 2013, when it was argued that doing so violated World Trade Organization rules.

With tradition going hand-in-hand with commerce, poultry suppliers don’t really have a reason to try and change domestic consumer appetites for the tails. In preparing his research into the missing treat, Carolan says he had to search high and low before finally finding a source of tails at a Whole Foods that was about to discard them. "[You] can't expect the food to be accepted if people can't even find the piece!"

Unless the meat industry mounts a major campaign to shift American tastes, Thanksgiving will once again be filled with turkeys missing one of their juicier body parts.

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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