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How Do Whales Hold Their Breath for Such a Long Time?

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By Chris Gayomali

Marine mammals have all kinds of wonderful adaptations to lead a comfortable life underwater, such as flippers and insulating blubber. Whales even have eyes that can see in monochrome, which is especially valuable deep beneath the surface where sunlight is at a premium.

But one of the whales' more fascinating adaptations is their enviable ability to hold their breath underwater for up to an hour at a time. Scientists know it has something to do with their myoglobin, a molecule in the blood that helps the body's muscles retain oxygen. In creatures like cows and humans, myoglobin is known for giving flesh its reddish tinge; seals and whales, on the other hand, have extremely high myoglobin concentrations that make their tissue look black.

Researcher Michael Berenbrink, a zoologist at the University of Liverpool, thought that was peculiar. "At high enough concentrations, [proteins] tend to stick together," Berenbrink tells BBC News. When too many proteins clump together, they become useless—dead weight.

So just how do densely packed myoglobin molecules in aquatic mammals keep from sticking together? BBC News reports:

The team extracted pure myoglobin from the muscles of mammals—from the land-based cow, to the semi-aquatic otter, all the way up elite divers like the sperm whale.

Led by researcher Scott Mirceta, this painstaking examination traced the changes in myoglobin in deep-diving mammals through 200 million years of evolutionary history.

And it revealed that the best mammalian breath-holding divers had evolved a non-stick variety of myoglobin. [BBC News]

The trick, apparently, is that the myoglobin of marine animals is positively charged, like one end of a magnet. Instead of clumping together, the molecules repel one another away, ensuring the blood stays loose and lubricated.

The whale's ability to hold its breath is, in a way, an evolutionary one-two punch: (1) The high concentration of myoglobin allows it to spend more time underwater in between breaths, and (2) the myoglobin's positive charge ensures the proteins don't clump together and kill the animal. Researchers say that mimicking this natural chemistry could have an impact in medical science, particularly in the way we perform human blood transfusions.

Berenbrink and his team even went so far as to reconstruct the myoglobin sequences of the whale's ancestors to pinpoint when the evolutionary adaptation may have occurred. "If you give me a myoglobin sequence, I can tell you if the animal is a good diver or not," says Berenbrink. Nature explains:

Using the reconstructed sequences from different animals to infer the electric charge on their myoglobin, together with information about the animal's body mass, the team was able to determine that an early whale ancestor—the terrestrial, wolf-sized animal Pakicetus—couldn't stay under water for much more than 90 seconds. But the larger, six-ton Basilosaurus, which appeared about 15 million years later than Pakicetus, could manage about 17 minutes. Many modern whales can remain submerged for more than an hour. [Nature]

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Big Questions
Why Does the Queen Have Two Birthdays?
CHRIS JACKSON, AFP/Getty Images
CHRIS JACKSON, AFP/Getty Images

On April 21, Her Majesty Queen Elizabeth II will turn 92 years old. To mark the occasion, there are usually a series of gun salutes around London: a 41 gun salute in Hyde Park, a 21 gun salute in Windsor Great Park, and a 62 gun salute at the Tower of London. For the most part, the monarch celebrates her big day privately. But on June 9, 2018, Her Majesty will parade through London as part of an opulent birthday celebration known as Trooping the Colour.

Queen Elizabeth, like many British monarchs before her, has two birthdays: the actual anniversary of the day she was born, and a separate day that is labeled her "official" birthday (usually the second Saturday in June). Why? Because April 21 is usually too cold for a proper parade.

The tradition started in 1748, with King George II, who had the misfortune of being born in chilly November. Rather than have his subjects risk catching colds, he combined his birthday celebration with the Trooping the Colour.

The parade itself had been part of British culture for almost a century by that time. At first it was strictly a military event, at which regiments displayed their flags—or "colours"—so that soldiers could familiarize themselves. But George was known as a formidable general after having led troops at the Battle of Dettingen in 1743, so the military celebration seemed a fitting occasion onto which to graft his warm-weather birthday. Edward VII, who also had a November birthday, was the first to standardize the June Trooping the Colour and launched a tradition of a monarchical review of the troops that drew crowds of onlookers.

Even now, the date of the "official" birthday varies year to year. For the first seven years of her reign, Elizabeth II held her official birthday on a Thursday but has since switched over to Saturdays. And while the date is tied to the Trooping the Colour in the UK, Commonwealth nations around the world have their own criteria, which generally involve recognizing it as a public holiday.

Australia started recognizing an official birthday back in 1788, and all the provinces (save one) observe the Queen's Birthday on the second Monday in June, with Western Australia holding its celebrations on the last Monday of September or the first Monday of October.

In Canada, the official birthday has been set to align with the actual birth date of Queen Victoria—May 24, 1819—since 1845, and as such they celebrate so-called Victoria Day on May 24 or the Monday before.

In New Zealand, it's the first Monday in June, and in the Falkland Islands the actual day of the Queen's birth is celebrated publicly.

All in all, just another reason it's great to be Queen.

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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Big Questions
What Is the Meaning Behind "420"?
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Whether or not you’re a marijuana enthusiast, you’re probably aware that today is an unofficial holiday for those who are. April 20—4/20—is a day when pot smokers around the world come together to, well, smoke pot. Others use the day to push for legalization, holding marches and rallies.

But why the code 420? There are a lot of theories as to why that particular number was chosen, but most of them are wrong. You may have heard that 420 is police code for possession, or maybe it’s the penal code for marijuana use. Both are false. There is a California Senate Bill 420 that refers to the use of medical marijuana, but the bill was named for the code, not the other way around.

As far as anyone can tell, the phrase started with a bunch of high school students. Back in 1971, a group of kids at San Rafael High School in San Rafael, California, got in the habit of meeting at 4:20 to smoke after school. When they’d see each other in the hallways during the day, their shorthand was “420 Louis,” meaning, “Let’s meet at the Louis Pasteur statue at 4:20 to smoke.”

Somehow, the phrase caught on—and when the Grateful Dead eventually picked it up, "420" spread through the greater community like wildfire. What began as a silly code passed between classes is now a worldwide event for smokers and legalization activists everywhere—not a bad accomplishment for a bunch of high school stoners.

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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