I think you all would get a kick out of my favourite parasite, the parasitic barnacle Sacculina Carcini.
There it is! Lives on the underbellies of crabs.
A female larvae attaches to the crabs underbelly, and stretches tendrils into the crabs body to provide nourishment for itself. But another purpose of this tendril infestation? To inhibit gonad development.
Now see, crabs carry eggs underneath them and, when the eggs spawn they use their claws to wave the offspring out to sea. They also care for the eggs attached to themselves, grooming them and protecting them. So that's this barnacles trick, it causes the crabs to do that for its own offspring, protecting its offspring and spreading the barnacle.
But what happens if the barnacle attaches to a male crab? After all, they don't show that behaviour.
Now in female crabs the effect of the gonad development inhibition is just a narrower abdomen and degenerated pleiopods.
But in male crabs it causes a feminisation. A broader abdomen, egg care and the motherly claw waving behaviour.
If you remove the parasite even, the formerly male host may start developing ovarian tissue, having undergone a sex change.
So essentially.
We have a barnacle that forcibly transitions and controls male crab hosts to spread its offspring.
Make the jokes as you will.
Some people will say I love this because I'm trans. No I just love this because I find it a fascinatingly complex thing to evolve. Parasite host manipulation is such an interesting topic, and one I would love to dive further into, even if I am scared of parasites.
But tbh, the reason I brought it up is because I know tumblr would love it for trans reasons.
