Moss could possibly be accused of being a bit, well, un-exciting. It doesn’t run about, it doesn’t maul things and it certainly doesn’t keep us awake at night with its mating calls.
But it does have sex.
And no, I don’t mean the usual pollen-lands-on-stigma, fertilisation happens behind closed doors, vaguely Victorian ‘higher’ plant sex. Moss sex is down and dirty (literally). It has swimming sperm which have to trek from the structures they’re produced in, the Antheridia (or ‘Moss testicles’ if we’re being anthropomorphic here) through a layer of water on the soil or the body of the plant or both, to reach the Archegonia (ok, just use your imagination) wherein they may find eggs, fertilise them and receive +10 Genetic Diversity Points for achieving sexual reproduction.
This is all fine and dandy and pretty cool, but the best thing about moss sperm is that you can see it under a microscope! I know this because I may or may not have spent an entire practical exclaiming variations on the theme of ‘OH MY GOD, IT WIGGLES! IT’S SO CUTE!’. My friend Peter, who is particularly good at coaxing sperm from Bryophytes (you can find him on Twitter @PeterMoonlight and admire his lovely photographs here), managed to film some. Therefore, here for your delectation and delight (no disgust, please, it’s perfectly natural) is a video of moss sperm, wiggling about like tiny green jelly beans with tails, searching in vain for Archegonia that they’ll never find (although most seem to be spinning aimlessly in circles, but I understand that’s pretty standard sperm behaviour). Tragic, really.
(Regarding their exact size, I am not entirely sure as Peter can’t remember what magnification he was using but I’d imagine in the order of 0.1mm would be a reasonable guess, please feel free to correct me if I’m wrong!)