Scientists built a zombie fungus cannon to test how spores spread

Bombs away.

Jackson Ryan Former Science Editor
Jackson Ryan was CNET's science editor, and a multiple award-winning one at that. Earlier, he'd been a scientist, but he realized he wasn't very happy sitting at a lab bench all day. Science writing, he realized, was the best job in the world -- it let him tell stories about space, the planet, climate change and the people working at the frontiers of human knowledge. He also owns a lot of ugly Christmas sweaters.
Jackson Ryan
2 min read

Covered in spores. 

Hans Hillewaert

It's the spooky season, so let me regale you with a story about the fungus, Entomophthora muscae. This fungus is particularly fond of the house fly. By fond I mean that if its spores settle on a fly, it then penetrates the insect's outer layer, infiltrates its circulatory system and sets up shop in the brain, controlling the insect's behavior. From the inside out, the fungus feeds on the fly and directs it to crawl to a high point so the fungus can shoot it spores further into the air -- and carry on the great circle of life.

A team of scientists from the Netherlands and Denmark was intrigued by how exactly spores were ejected from the corpse of a dead fly. Because it's quite difficult to control experiments of "wild" fungus and examine how the spores are being jettisoned, the team decided to build its own zombie fungus cannon that mimicked the real thing.

And the real thing is, it's no joke -- it fires spores at about 10 meters per second (or 22 miles per hour).

The cannon's construction is detailed Tuesday in the Journal of the Royal Society Interface, revealing some of the likely inner workings of the spooky zombie fungus' artillery. The artillery is an abundance of "stalks" that are basically cannons filled with pressurized liquid similar to water. The team studied the way pressure builds up in the stalks and how fast the spores end up blasting out as a result. 

Studying the fungal cannon's geometry and elasticity, the team was able to pull apart some of the dynamics associated with the spore gun. One of the chief findings is how the ejection velocity slows as the cannon gets bigger. A logical finding, but one that helps scientists better understand the unusual dispersal method and how the fungus gets from host to host. 

You may be thinking, "that seems like a bit of a poor system -- what if there are no other flies around?" and that's a good question. Other teams have shown in the past that infected flies are quite attractive to non-infected flies, so when the fungus is ready to unload the cannons, there's likely to be somewhere for the spores to go.

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