Life Science The mind-controlling parasitic worms creating so-called ‘zombie snails’

The mind-controlling parasitic worms creating so-called ‘zombie snails’

Two zombie snails in full flight – the parasitic worms enlarge their host's eyestalks and pulsate vibrantly. Photo: Getty
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Some wonders of the natural world can leave you truly awestruck; others can leave you recoiling in horror; and sometimes, they have the potential to do both.

The torture-like coexistence of a parasitic worm and its ‘zombie snail’ hosts is the latest to usher a polarising response by online audiences after striking footage was uploaded to social media.

The flatworm, known as Leucochloridium paradoxum, can be seen in full flight, with its broodsacs pulsating inside the snail’s bulging eyestalks to mimic the movements of a small caterpillar. And this is entirely by design.

In order to continue the species’ lifecycle, the parasite requires the attention of passing birds, who are duped into pecking out the snails’ eyes and inadvertently digesting them.

The broodsac continues to breed inside the bird’s intestinal tract, which are eventually excreted in its faeces, ready to be consumed by another innocent snail host.

But that’s not all.

If the parasite becomes aware that its host is sitting in a location unlikely to be discovered, it gains control of the snail to drag it out into the open – whether it be atop a tasty-looking leaf, or a taller branch.

And for good measure, it has the capacity to castrate its host, ensuring it soaks up enough energy to thrive and perform its vibrant dancing act.

This unfortunate tragedy is disgusting, and yet, strangely fascinating.

In somewhat buoyant news, snails’ eyestalks are known to regenerate, only to potentially become home to another round of parasitic pain.

Regardless, the prospect of a world overrun by the ‘zombie snail’ – while perhaps a little overblown – has captured the imaginations of a fervent social media following.

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