The name “rhizocephalan barnacles” sounds rather harmless, but this little creature does stuff that simply blows the head right off most biologists.
The Wikipedia entry is a big clinical, so is there anything that captures the true horror here?
Yes there is, deep sea news does a fine job …
You’re lingering on the shoreline, the warm sun on your back, cool water in your gills. You’re reached a large size, dodging the many dangers of youth. Life is going well. But today you begin to feel strange– maternal almost– as if there is something growing inside you, and in fact, something is.
Its roots are crawling through your tissue, your gut, your brain. Its a rhizocephalan barnacle, and it’s about to take you over.
Your new tormenter is a member of one of the strangest groups of animals known. The adult female body of the rhizocephalan is twisted and deformed, not resembling in any way its barnacles cousins living on rocks near shore. She has lost her hard shell, her legs, her eyes, and transformed into sickly yellow roots and sinuous twisting filaments that are slowly grow like black mould through your tissues. But she looked normal once: when she was young. As a juvenile she looked like a normal barnacle larvae, only a few millimeters long. But her juvenile body had one terrible difference: her head was tipped with a needle protruding form her shell. When she found you, she used her body like a hypodermic syringe: stabbing you and injecting her own cells under your skin. All that’s left of her is now growing and spreading like a cancer through your system. You’ve stopped growing. Her fibrous tentacles are consuming your extra energy.
Just when it seems it couldn’t be worse, your abdomen explodes. You’re now sterile, and her gonads are erupting out from where your genitals are. Her tumorous ovaries now attract a male rhizocephalan larva, who injects his own cells into her. These grow into testicles within her body. She now has everything she needs for her next takeover.
But none of this bothers you now. She has woven her threads through your brain. She’s been secreting chemicals to control you– you’ve forgotten who you are. You now believe you are female, and the bulge in your abdomen is a brood of your own eggs. Moreover, you are about to give birth. You care for and clean these eggs, as if they were your own.
You now have my full permission to go and throw up.
Want to see one?
OK, here you go, it is a picture of one bursting from the abdomen of a crab
I should perhaps also point out that rhizocephalan only goes after crustaceans, so it is still OK to swim.