I was watching Spike TV’s Manswers the other day, and one bit of trivia I couldn’t understand because of the way they phrased it.
The way they set it up was that if sperm were human sized, for example, the distance they have to swim would be like a human swimming across the Pacific Ocean. Then, they said sperm travels at 30 mph (I’m assuming here that they continued the whole “if it was human sized” thing,) but I wasn’t sure if they swam at this speed or were ejaculated out at this speed.
Also, they compared sperm speed to Usain Bolt, but this doesn’t make sense either as sperm are swimming.
So what is the relative speed of sperm, not including ejaculation?
Claims of it being equivalent to swimming the Pacific are wildly exaggerated. Average sperm size is about 25 micrometers; scaling that up to human size (let’s call it 2m for simplicity) is a factor of about 80000. The length that a sperm cell has to swim is of the order of 20cm, or 0.2m. 0.2m * 80000 = 16,000m - 16km or 10 miles. Not really Pacific-sized.
However, it must be noted that sperm are swimming through a far more viscous medium than water, which I have no idea how to account for. But even if it’s a factor of 10 difference, it would still be only like swimming 100 miles, rather than the thousands of the Pacific.
The only way to test this is to get a Pacific Ocean-sized space, fill it with semen, and have someone swim across it. Now seeking volunteers. Come one, come all.
Mythbusters did it! The viscosity slows you do down by the same factor that it makes it easier to push forward. But, considering their 80,000x smaller size (measuring linearly!), they don’t swim as we know it.
Btw, sperm don’t have to swim 20cm. They just have to cross the cervix.