An Aussie woman’s strange find in her bathroom has led to a fascinating – and rather creepy – discovery that sounds like something straight out of a horror movie.
In central Victoria last week, the woman found a long, brown ‘string’ next to her bath that appeared to be moving. Curling up on itself, no apparent head or tail can be seen.
Next to the worm was a dead huntsman spider, and while it may not have seemed like an important detail at the time, advice from a local field naturalists Facebook page soon revealed the astounding relationship between the two creatures.
The worm is likely a parasitic worm – a mermithid nematode or horsehair worm – using the spider as a host, University of Queensland entomologist Dr Kayvan Etebari told Yahoo News.
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As part of its gruesome lifecycle, the worms take over the host’s body, literally eating it alive from the inside out.
“Inside the host, both mermithids and horsehair worms develop over time by absorbing nutrients from the internal fluids of the insect or spider. They do this in a way that allows the host to remain alive and active for most of the parasite’s development,” Dr Etebari said.
“This survival of the host is crucial to the worm’s life cycle. The host continues its normal activities until the worm is ready to emerge, at which point it often kills or severely weakens the host in the process of exiting, usually near a moist environment.”
The parasites typically infect crickets, beetles, cockroaches, grasshoppers and spiders and are – thankfully – not harmful to humans or pets. Birds and reptiles are also safe.
A similar case from the 90s, which was featured at the Australian Museum, involved another dead huntsman next to a coffee cup with a long writhing worm inside the leftover coffee.
Similarities between parasitic worms and zombie ant fungus
You may have heard of cordyceps, a fungus that infects a host and alters its behaviour with often lethal consequences (it was the concept behind the popular zombie series The Last of Us). Dr Etebari noted some similarities between the two.
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“Both types of parasites also exhibit a fascinating ability to manipulate the host’s behaviour — most notably driving them to seek out water, which is essential for the worm’s emergence and continued survival,” he said.
“While the mechanism is not as well understood as in fungi like cordyceps, the manipulation is still notable. This behavioural change benefits the worm by ensuring it exits the host in a suitable habitat. Although Mermithids and horsehair worms are different taxonomically, their manipulation strategies are quite similar in outcome.”
What should you do if you find one of these worms?
Mermithids and horsehair worms are most likely to be seen after rainfall or in damp areas where their insect hosts thrive.
If you happen to find one in your home, Dr Etebari insists there’s no need to panic.
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“The worm can be gently removed using a tissue or gloves and placed outside in a shady, damp area. They are harmless to humans and pets, cannot reproduce indoors, and won’t infest your home. Seeing one may be a little unsettling, but it’s a rare glimpse into a remarkable ecological interaction between parasites and their arthropod hosts,” he said.
Interestingly, scientists are now using microscopic nematodes as an environmentally friendly pest management tool.
The worms seek out and infect pests in the soil, before releasing bacteria that kills the insect and allows the nematodes to reproduce.
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