Tardigrades—a.k.a. moss piglets or water bears—are the scientific gift that just keeps on giving. Everything about these microscopic animals is extreme. They’ve been on Earth since long before the dinosaurs. They can withstand blistering cold, intense heat, years without food or water, and hanging out in the vacuum of space. They’re practically unkillable. So it makes sense that their sex lives would also be interesting.
That's why scientists have produced a video of two moss piglets having sex. The researchers/cinematographers responsible for the tape described the tender-yet-disgusting process in an article in the Zoological Journal.
The sex you’re about to watch is not representative of all tardigrades, just one species, Isohypsibius dastychi. There are more than 1000 different tardigrade species out there, and not all of them reproduce sexually. But I. dastychi certainly does.
For those of us unaccustomed to watching tardigrade sex (we're going to assume that's mostly everyone), here’s what’s happening. The female (L) has molted and laid eggs inside her discarded old skin. The male (R, perpendicular) has curled himself around her and is stroking her as he ejaculates onto the eggs.*
The researchers write that the action was “much more complex than expected,” and note that this “mutual stimulation” went on for at least an hour.
Not bad, little tardigrades. Not bad.
*We did warn you that this would be disgusting.