Real Life Zombies in the Animal Kingdom
Zombies have long been featured in movies, games and television. Fortunately, zombies from these media are just fantasy! But did you know that there are real-life zombies out there in the wilderness? There are many examples of parasitic fungi, insects and viruses that take over the minds and bodies of their hosts. Let’s dive in and learn a little about these strange life forms!
The periodical cicadas that emerged this spring were loud and in your face. But did you see any with white abdomens? This indicates that the cicada was infected with the Massospora fungus. This fungus eats away at the cicada’s abdomen and reproductive organs while releasing psychoactive compounds that take over the cicada’s mind. These compounds compel the cicadas, including males, to make the clicking sounds of a receptive female. If any male falls for the trick, the infected cicada will try to mate (even when they no longer have reproductive parts), thus spreading the fungus.
One real-life zombie-maker has actually made its way into popular media. The Cordyceps genus of fungus has many species that use insects for their hosts. However, in the Last of Us video game series, this fungus has evolved to use humans as hosts and has wreaked havoc on civilization. In reality, this fungus is much less frightening – unless you’re an ant! When the spores of the fungus enter an ant, filaments spread throughout the body, taking over the ant’s muscles. The fungus forces the ant to leave its foraging area and climb a plant to find an ideal place to spread spores – often right above the rest of the ant colony. Then, the zombie ant clamps its jaws on a leaf or stem. Once securely attached to the plant, the fungus kills the ant, fills its body, and sprouts out. Typically, the fungus’s reproductive parts grow right out of the ant’s head!
Any discussion of zombie insects would be remiss without a mention of wasps. There are many species of parasitic wasps, but some Braconid wasps have evolved to turn their hosts into zombie bodyguards! The adult wasp finds freshly hatched caterpillars and deposits dozens of eggs inside. Once the eggs hatch, the wasp larvae feed on the caterpillar’s insides. Somehow, these larvae know not to eat the caterpillar’s vital organs, and the caterpillar continues its life unaware of its situation. When the wasp larvae are ready to pupate, they eat their way out of the caterpillar and begin spinning their cocoons. The caterpillar not only survives this ordeal, but begins behaving against its own interest. It reinforces the wasp cocoons with its own silk, then it stops feeding and stands guard over the wasp pupa. As the wasps develop, the caterpillar fiercely defends them from predators. By the time the adult wasps emerge, their bodyguard will have starved to death. Scientists still don’t know the exact mechanism for this zombie-like behavior.
These are only a few examples of the many ways that nature has created zombies. While we learn about them and wonder at the darker side of Mother Nature, we can be thankful that these parasites don’t count humans among their hosts!
Nature Interpreter, Sharon Woods