This post is going to end with a bone-eating snotflower and kinky sex. But first, some background:
Evolutionary biology began with a simple principle: choosy females, slutty males. The idea was that eggs are energetically expensive – the egg itself is big and filled with baby food, and then the female still has to bear and maybe raise the babies. In contrast, sperm are energetically cheap – males can easily produce millions a day, fertilize all the eggs they want, and never have to deal with the consequences.
But of course science is a human endeavor, and the men (mostly men, at that time) saw what they wanted to see – nature reflecting human societal mores. The huge influx of women into biology coincided with the onset of genetics, and suddenly slutty females and homemaking males appeared everywhere in nature. (Incidentally, homosexuality is also found in nature – the gay penguins being the most famous example – but that is a post for another time.)
The most extreme example of the slutty female and passive male is found in the bone-devouring worm Osedax, which was just discovered in 2004. One Swedish species is Osedax mucofloris, which the bone-eating snotflower I promised you.
Osedax worms live only on dead whales that fall into the deep, feeding on their oil-soaked bones. They are quite fetching, with luscious red and white plumes and a pink body, if you don’t mind that their nickname is “zombie worms.” (Personally, I think that if eating carrion made you a zombie, we’d all be shuffling and moaning already.)
But the only Osedax you’ll see when toodling around your local whale carcasses 2 miles below the surface are the females. This puzzled researchers at first – where were the males? Were they valiantly hunting down live whales? Were they traveling around to the ladies of many carcasses, leaving broken hearts in their wake?
Nope. They were lounging about in the tubes of the females, barely developed, still trailing bits of egg yolk. Each female had a harem of dozens of microscopic males living inside her, doing nothing but fertilize away. Now, you could make the argument that they have a pretty nice life – free food and all the sex they want. But it’s hardly the stereotype of the mighty hunter.
Nature doesn’t give a crap about silly human preconceptions because evolution is all about what works. Having dwarf parasitic males is pretty common in the deep sea, where life is spread out and food is scarce. For Osedax, dependent on a few widely spaced dead whales and unable to move once they’ve settled in, it works perfectly.
But don’t take my word for it – here is Dr. Nerida Wilson of the Scripps Institution of Oceanography’s Marine Invertebrate Phylogenetics Lab. (The PI, Dr. Greg Rouse, was one of the original Osedax discoverers.) The film is by Laura Escobosa.