Reminder: Period Blood Does Not Attract Sharks

Photographed by Ashley Armitage.
Periods take the blame for way too many things. A woman has emotions? Must be on her period. She questions a powerful man who's made misogynistic comments? She must have "blood coming out of her wherever."
With all the period myths that abound, however, there's one we had hoped everyone knew was false: the idea that period blood attracts sharks.
But professional surfer Laird Hamilton proved that that myth is still alive and well in an impromptu interview with TMZ.
There has apparently been an uptick in shark sightings in Southern California recently, and since Hamilton spends a good amount of time in the water, TMZ thought he might have a wise word about why the sharks seem to be coming out in full force lately.
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Instead, he blamed menstruating women for enticing the sharks.
"The most common reason for being bitten is a woman with her period, which people don't even think about that" Hamilton told TMZ. "Obviously, if a woman has her period then there's a certain amount of blood in the water."
While it's true that sharks are attracted to blood, experts have repeatedly dispelled the idea that someone swimming in the ocean while on their period becomes instant shark bait.
Some experts says that human blood isn't as attractive to sharks as the blood of fish and other marine creatures.
Ralph S. Collier, a shark behavior expert, told Mother Jones in 2012 that "our blood is different from a sea otter's blood or cetacean blood. Our blood is from a terrestrial environment." The scent of human blood, he theorizes, doesn't send the same signal to sharks that there's a ready-to-eat meal nearby.
That lines up with one thing Hamilton said that actually made sense — that most shark attacks are a case of mistaken identity, meaning that sharks don't want to eat people but when they do attack it's often because they thought a human was a seal or fish.
Even if they were attracted to human blood in the same way as fish blood, experts have given a few other compelling reasons a period wouldn't likely result in a shark attack.
For starters, the liquid that comes out of a uterus every 28-ish days isn't purely blood. It's a mix of blood, bacteria, vaginal mucus, fluid, and tissue — so it doesn't actually smell like the blood from any other part of your body.
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Dr. Tricia Meredith, a biologist at Florida Atlantic University, told Broadly last year that sharks can detect odors from their prey at levels of one part per billion. That's pretty impressive, but given the vastness of the ocean and the minuscule amount of blood that actually comes out with menstrual fluid, it still makes it relatively impossible for a shark to sniff out someone who is menstruating.
So, please, let's just let this myth swim with the fishes.
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