(this article was also submitted to fuckyourbrain.com, soon to be featured in the 3D magazine)

The Cruel World of Mind-Altering Parasites

A bullet ant (genus Campanotus) begins to twitch around and wiggle its antennae in a very strange way, and its tail end tucks up conspicuously against its body. Its companion worker ants take careful notice of the behavior and quickly move it far away from them. They know it has been infected with a fungus that is eating through everything but the ant’s vital organs, and its last task will be controlling the brain. The ant continues to fumble, wandering around seemingly aimless. The fungus then triggers a reaction in the ant’s brain that will lead it to a trail of non-existent pheromones. In a couple of days, it will climb to the top of the highest leaf it can find on a branch reaching towards the sun, something it has never done before in its life. Once perched upon the leaf, it will chomp down with its powerful mandibles. The fungus that has been infecting the ant, cordyceps (Paraponera clavata) will burst a sun-seeking tendril out of the now dead ant’s head. Its dead carcass will become a planter for the alien-looking fungus to bask in the sun. Its spores will fly into the air, and hopefully germinate in the body of another unsuspecting ant.

Next is an orb spider, Plesiometa argyra, who, on a normal day, builds impeccably precise webs to catch prey. A pompilid wasp (Hymenoepimecis argyraphaga) that is ready to lay eggs decides today will be different. It attacks the spider and temporarily paralyzes it long enough to lay a single egg on the outside the spider. Once it regains the use of its body, the spider returns home as if nothing has happened. Meanwhile, the wasp larva clings to the back of it and feeds from the spider’s insides through small puncture wounds in its body. As the larva starts to grow over the next two weeks, the spider is suddenly inclined to build something it normally doesn’t- a nice, cozy cocoon for the larva. Eventually the spider will slump down into this cocoon until the wasp larva is finished eating it alive and now has a nice, safe shelter to stay inside.

Not to be outdone by its land counterparts is the sea parasite, Sacculina, a genus of barnacle. Normally, barnacles attach themselves to harmless things like rocks, piers, and boats. Sacculina opt to live inside of live crabs, sometimes infecting as much as 40% of a crab community. The female larvae attack a crab and find a vulnerable joint to nestle down into. It then injects itself into the crab with a needle-like appendage and then sloughs off most of its body. Once inside the crab, it develops into root-like growths that spread throughout the crab’s body, working its way into the egg sack in the genital area. The genital plate is forced open as the sack grows. The crab starts to look like it has Elephantiasis of the testicles, but here’s where it gets really horrifying- the parasite changes the hormone balance in the crab, rendering it female and sterile no matter what it was before. Male Sacculina are now able to impregnate the female. The crab loses most of its functions, including regeneration and molting and is now a brainwashed mother whose only purpose is to care for her barnacle young. As they are born, the crab cares for them as if they were her own, and is free to repeat the process all over should another Sacculina invade.

Best of all, perhaps, are parasitic flatworms (Leucochloridium paradoxum) that turns a normal snail’s life into a horror movie. An innocent snail crawls along and finds a delicious pile of poop to feast on. A few days later, something strange begins to happen- the snail’s eyestalks become host to flatworm larvae and begin to bulge and change to a grotesque shade of green. Snails are nocturnal and usually unappealing prey to birds because of their foul-tasting slime. They also need to stay moist and generally avoid sunlight. Compelled by the parasite, the infected zombie snail marches right out into the open daylight and its swollen, pulsating eyestalks mimic juicy, writhing worms. A bird can’t resist these tasty looking treats and pecks the snail’s eyestalks clean off. The snail will likely survive this heinous attack, but unfortunately, the flatworm larvae will still remain. As the snail regenerates new eyestalks, the flatworms will infect them again. Meanwhile, the bird has a digestive tract growing full of flatworm eggs, just waiting to be pooped out. It’s only a matter of time before another unsuspecting snail comes across them.

There are dozens of similar behavior-altering parasites, each as fascinating as the next. Most of these parasites are specialized to a single species of host. The large majority infect insects or creatures on the low end of the evolutionary scale. There are some exceptions, including Toxoplasma gondii which lives in cats and infects humans. Toxoplasma gondii also infects rats and makes them lose their fear of cats- an infected rodent will waltz right up to cat’s hangout spot, only to be eaten and live inside the cat’s intestines long enough to get back to its preferred host, a human. Studies are still being done on the effects of Toxoplasmosis, but it seems to produce introverted and anti-social tendencies in the host, along immune and neurological problems.

For those interested in even more of these parasites, YouTube has a plethora of videos in their full, gruesome glory. I highly recommend a viewing of them at your next social gathering. There will be no doubt left that nature is a tough, strange world.

(All photos are licensed under Creative Commons)