Science is everywhere. Even in the realm of zombies. Because zombies actually exist. they may not look like those in Dawn of the Dead, but they are even scarier. Because they are real. And being zombified in nature is fate worse than death. Smithsonian magazine has a fun article on the scariest zombies in nature. Zombie ants colonized by a fungus who turns them into robots that mechanically climb to the highest spot possible, just in time for the fungus to burst out of the ants head and spread its spores as far as possible. Other animals, such as snails, are colonized by parasitic worms that invade even its eye stalks and change them into brightly colored pulsating organs that attract birds. Once the birds eat the hapless snail, the parasitic worm lays hundreds of eggs inside the bird. Read the article for more details on zombies in nature.
One zombie by itself is not necessarily very scary, but in B movies from, Night of the Living Dead to Zombieland, Hollywood’s animated corpses have a nasty habit of creating more of the walking dead. Controlled by some inexplicable force, perhaps an intensely virulent pathogen, the main preoccupation of a zombie is making other zombies. The story line is pure drive-in movie schlock, yet the popular mythology of zombies has lately been spattered with a coating of biological truth. There actually are organisms that have evolved to control the minds and bodies of other creatures, turning once normal individuals into dazed victims that fulfill the parasite’s need to reproduce itself.
Some of the most successful zombie-masters are fungi from the genus Ophiocordyceps. The parasites infest many kinds of arthropods—from butterflies to cockroaches—but it is among ants that the fungi’s ability to control other beings’ behavior is most apparent. One prototypical scenario is found in Costa Rica, where infected bullet ants (Paraponera clavata) climb to a great spore-sprinkling height before the fungus erupts.
In the jungles of Thailand, the fungus Ophiocordyceps unilaterius parasitizes Camponotus leonardi ants, which forage on the ground and nest in the canopy. When infected, these ants shamble toward “ant graveyards,” where they bite down on the undersides of leaves, anchoring their fungus-infested husks at a level of the forest with just the right humidity and temperature to allow the fungus to grow properly. When Sandra Andersen of the University of Copenhagen and colleagues placed the bodies of infected ants higher in the canopy, the parasites grew abnormally, and infested ants placed on the ground were eaten by other insects. “The fungus is sensitive to UV light, and the heavy rainfall in a tropical forest would most likely also be able to damage the fungus,” Andersen says. “The position of the ant on the underside of the leaf limits the exposure of the parasite.” The fungus drives the ants to seek out specific places to die that best benefit the growth of the fungus.
How does a fungus learn how to disrupt a brain and act on it?
God taught the fungus to do this. Because he is a loving god :-)
Like everything else, the fungus does not know, but it adapted to hijack the ants nervous system for its purpose. Evolution, baby. Or in this case, evilution. Bwah-ha-ha-ha-ha!
Wonder what would have preceded that fungus.
There are many parasitic fungi. This one was probably preceded by a parasitic fungus that did not control the ant's behavior, just parasitized the ant, and spread the spores by a more standard mechanism. All of us are actually colonized by fungi. Our immune systems do not let them take over. But people with AIDS, for example, or immunosuppressed patients, can become colonized by fungi and actually die.
Well, I'm glad to know all this zombie stuff didn't came out of nothing or out only from human imagination... I expect that the stories of Dracula have some kind of truth in them and we know that the Frankestein stories can be real...
Not to mention Dr. Jekyll and Mr Hyde! I live with one of those! :-))
More scary zombie insects:
A bug expert discusses a sinister virus that causes gypsy moth caterpillars to self-destruct
October 29, 2011 | 3|
Name: Kelli Hoover
Title: Professor of entomology, Pennsylvania State University
Location: University Park, Pa.
You recently identified a gene known as egt that allows a specific group of viruses to control the behavior of caterpillars. Tell me what it does.
Gypsy moth caterpillars have a normal behavior they do every day. They climb out onto the leaves to feed at night. During the day they climb back onto the branches or bark to hide from predators because they’re very obvious when they’re on the leaves. But once caterpillars are infected with these viruses, known as baculoviruses, their levels of the EGT protein become elevated. Once that happens, you find them on leaves in the middle of the day. It’s like: “What are you doing here?”
And how does that harm the caterpillars?
Eventually they climb to the tops of trees, where they get converted into a sac of virus that liquefies and rains virus particles down on the foliage below so that new hosts can be infected by eating the virus on the leaves. Egt is manipulating the insect to die in the right location to transmit the virus to new hosts.
What is the mechanism by which the gene does that?
In short, we don’t know, but we have a couple of ideas. It was already known that egt blocks molting in caterpillars. What happens when the insects molt is they stop feeding for quite some time; if they’re kept from molting, they’re kept in a feeding state. It’s possible that because they’re being stimulated to keep feeding, they’re staying up in the tree when everybody else is climbing down.
Read the rest here.