COSMOS MAGAZINE
Zombies are everywhere in fiction, from movies to TV shows, video games to books.
But nature has its own version, where parasites and pathogens turn hosts into mindless, obedient carriers.
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Gordian Worms
Gordian worms, or horsehair worms, grow up to 30 cm long inside insects like grasshoppers and crickets, hijacking their host’s brain to complete their life cycle.
They release molecules that likely alter the insect’s nervous system, forcing it to leap into water — where it drowns and the worm escapes to reproduce.
Image: Greg Barton
Zatypota Wasp
Amazonian, Zatypota wasps lay eggs on social species of spider (Anelosimus eximius).
The eggs hatch into larva that drinks the spider’s internal fluids and takes over its brain, turning it into a zombie caretaker.
Image: Greg Barton
The infected spider abandons its colony to build a protective web for the larva, which then kills and eats the spider before emerging as an adult wasp.
Cordyceps Fungus
Cordyceps fungi infect insects and take over their brains with chemical signals from fungal secreted proteins.
The fungus then consumes everything inside the host, killing it to use those nutrients to sprout a fruiting body out the top of the host’s head. Spores form and drift off to infect more unwary hosts.
Image: Greg Barton
Rabies Virus
One of the few viruses that can mimic classic zombie symptoms – minus the rotting corpse – is rabies. A viral infection spread through animal bites, it causes aggression, confusion, and compulsive biting.
The virus travels through nerves to the brain, where victims either become paralysed or enter the “furious” phase, which includes hallucinations, extreme agitation, and hydrophobia (fear of water).
Image: Greg Barton
Toxoplasma
Toxoplasma gondii is a single-celled parasite that reproduces in cats and infects the brains of rodents – and people. Infected mice lose their fear of cats and may even be drawn to them, increasing the chance of being eaten.
Up to half the world’s human population may carry the parasite without symptoms. Studies suggest it’s linked to impulsivity and aggression.
Image: Greg Barton