Video: High-speed cameras reveal that dung-dwelling fungi spores achieve amazing acceleration when they are dispersed

High-speed cameras captured the squirt-gun action of dung-loving fungi (Image: Yafetto et al.)

They’re tiny, gooey and they grow on dung. But that does not stop fungi spores from being the fastest flyers in nature.

Using high-speed cameras, researchers have for the first time accurately measured the speed at which some fungi propel their spores. The images show in detail how microscopic dung-loving, or coprophilous, fungi use a squirt-gun action to propel their spores.


The fungi degrade the millions of tons of dung produced by cows and other herbivores each year. To reproduce, their spores must be eaten by herbivores, yet few animals will graze on the grass next to their own dung.

To overcome this obstacle, dung-dwelling fungi have evolved tiny catapults, trampolines and squirt guns that propel spores and spore packets up to 2.5 meters away.

Goodbye, cow pie

Nicholas Money at Miami University in Oxford, Ohio, and colleagues filmed the squirt gun action of four species at 250,000 frames per second.

They found that the spores, measuring between 10 micrometres and half a millimetre, are launched at up to 25 metres per second. Although impressive, that makes them slower than had been estimated by mathematical models.

But the acceleration of the spores still puts them in a class of their own. “One minute they’re standing still on a cow pie, and a millionth of a second later they are travelling at 25 metres per second,” says Money.

His colleagues measured accelerations up to 180,000 g – the fastest airborne acceleration seen in the living world. In comparison, a jumping antelope accelerates at 1.6 g, astronauts experience maximum acceleration of less than 4 g during a Space Shuttle launch, and fleas accelerate at 200 g. Jellyfish stingers are fired at 40,000 g in water.

“The fastest spores travelled more than 1 million times their own ‘body’ length in one second,” says Money. “A 1.8-metre human travelling at 1 million times his or her body length in one second would be travelling at a velocity of 1.8 million meters per second, which is more than 5000 times the speed of sound.”

Sap squirters

To understand why mathematical estimates based on the distances travelled by the spores had been wrong, Money’s colleague Diana Davis looked at the droplets of liquid expelled with them.

The squirt guns expel their contents by osmotic pressure. So from the composition of the sap, Davis was able to calculate the pressures that would develop inside. The mathematical calculations had suggested that these pressures must be very high in order for them to spit the spores metres away.

Instead, Davis found that the squirt cells are under no greater pressure than other kinds of fungal cells. The researchers say the models must have over estimated the drag that air exerts on the tiny droplet.

Journal reference: PLoS ONE (DOI: 10.1371/journal.pone.0003237)