Oct 26, 2008

Body-snatching Barnacles and Zombie Crabs

I stole the title to this post because I loved it so much (and I couldn't think of something better). Turns out not all barnacles are conical-shelled crustaceans that began life as free-floating plankton. Some barnacles are the scourge of any crab they encounter.

When the female Sacculina barnacles invades a crab's body, she does so in an amorphous gelatinous form. She then sends roots throughout the crab's body and begins to feed on it while she grows into a tumorous growth. She even carves out a little spot (the barnacle equivalent of a studio apartment) for the male Sacculina so that she might have baby Sacculinas. But the barnacle doesn't stop there.

Photo source: hku.hk
She seizes control of the crab's mind and forces it to do her bidding. The crab ceases to grow and looses the urge to mate. Instead, it unwillingly devotes itself to caring for the barnacle's eggs, using all of its time and resources to do so (disciplining the barnacles youngsters when they get rowdy, reading to them, singing lullabies just before nap time, etc.). The barnacle even alters the physiology of a male crab so that it becomes a female, so that it might better tend to the eggs.

Come on. I know all creatures need to make a living, but some just take it too far. Some parasites manage to be beneficial, and some become tongues. This one just owns its host in every conceivable way and then discards it. My neighbor has a mooching, parasitical son, who I now suspect might be a variant of the Sacculina barnacle.

Thanks for the link, anonymous.


Anonymous said...

another weird thing about these creatures is that they start out as little bug-like things that find a crab and look for a weak area like a leg joint. They stab their legs into the crab and INJECT THEMSELVES into it through their hollow appendage.

Anonymous said...

Eww gross! Poor crab =(

Vanessa said...

You have just got to be kidding on this one!
Holy smokes, and humans are supposed to be the superior species - we have nothing on this brilliant barnacle.
Poor crabs, but kudos to the unmatched self preservation of the barnacles.

Alison said...

These creatures are ugly in appearance, attitude and action. I just hope they never mutate into a land-based form. And thanks, Linty, for adding those delectable details.

I would go take a bath now, but I'm afraid of the water.

Arallyn said...

lol, I read about both this creepy parasite and the last one in Carl Zimmer's book "Parasite Rex"...I don't know why I didn't think of sending them in!

If anyone else likes science that's still entertaining to read, it's a great, albeit somewhat frightening, book.

Anonymous said...


Don't forget the parasitic trematodes that invade and coat fish brains. The invasion causes fish to swim near the water's surface, act jerkily, turn on their side and flash their light colored undersides. This makes them much easier prey for shore birds where the parasite will start the parasitic cycle again.

Or Dicrocoelium dendriticum, the lancet liver fluke, that manipulates an ant's nerves and causes them to climb tall grass blades and clamp on with their mandibles, hoping to be eaten by grazing animals in order to start the parasitic cycle again.

Or finally the fungus cordyceps that infects ants' brains, causes them to climb a tall tree, sink their mandibles into a branch then die, whereupon the fungus grows stalks out of the ant's body and releases spores that fall onto the forest floor in order to start the parasitic cycle again.

Parasites rule the world. Just look at Washington DC. :o)

Anonymous said...

And even more disturbing is the gordian worm that grows in its host (grasshoppers, locusts, and beetles) then compels the host to commit suicide by jumping in the water so it can emerge. It can also survive predation my crawling out the mouth or nose of the predator that ate its host. Disturbing videos of the gordian worm and cordyceps can be found here:

You've been warned.

Arallyn said...

gee anonymous, thanks for reminding me of everything else that was creepy (but fascinating) about the book ;)

W. A. Whipple said...


Anonymous said...

holy crapface

Anonymous said...

Wow... Totally sick! I only knew about cordyceps (a much beloved Chinese traditional medicine, yum!), gordy worm and the mind-control wasp as brain-masters from the sickth dimension.