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Sperm Doesn’t Move the Way We Thought It Does

Think of them less like tadpoles and more like playful otters. Awww!

Our body mirrors patterns in nature. The iris of our eyeballs look like space galaxies; our lungs contain a fractal system like that of a tree. Along those lines, we’ve always thought that human sperm swam like little fish, but we’ve recently learned differently: It turns out, they swim like playful otters

Otters love to propel themselves by twisting and spiraling forward, moving through water like a drill. It’s very cute! As new developments in 3D microscopy have revealed, this is precisely how sperm swim, as well. Rather than moving their little tails back and forth in a wiggling motion, researchers at the University of Bristol and the Universidad Nacional Autónoma de México have discovered that sperm are capable of only rotating in one direction. “The sperm is not even swimming, the sperm is drilling into the fluid,” study author Hermes Gadêlha told Live Science

The concept of sperm “swimming” is one we’ve had a scientific basis for since 1677, when Dutch scientist Antonie van Leeuwenhoek developed a microscope with far more advanced clarity and magnification than the earliest microscope, created 90 years prior. As any proper scientist would, Leeuwenhoek had the inclination to see what his own semen looked like under 270x magnification. At that level, sperm appears to be swimming, and so we’ve assumed this to be the case for the last 343 years. 

Thanks to some cool advancements in microscopes and the technology to capture high-speed footage, we’ve since had the brilliant idea of placing some spunk under a microscope once more to confirm Leeuwenhoek’s belief. And whaddayaknow, sperm contains spinners, not swimmers. 

Beyond turning your entire world upside down, this research might also lead to some advancements in understanding fertility. Earlier this year, researchers at the University of Birmingham discovered that sperm with less mobility in the lower segments of their tails were more efficient and speedy than their seemingly more mobile peers. Research establishing a connection between sperm tails and spinning hasn’t yet been conducted, but it’s possible they’re related. 

Just as with the tails, this information may help researchers in the development of effective lab-grown sperm and various fertility treatments. Until then, though, we’re all gonna have to adjust to the idea that sperm aren’t little swimming fish. Playful otters are pretty cool too, though.