This weird trick will help you summon an army of worms - Kenny Coogan
In the middle of Florida’s
Apalachicola National Forest,
a bizarre, almost magical scene
is unraveling.
Sliding a metal strip over a wooden stake,
a master summoner is sending deep croaking
noises reverberating through the area.
And, as if in a trance,
hundreds of earthworms
begin emerging from the soil.
This is worm grunting, also called
worm charming or fiddling.
It’s a tradition that’s been practiced
for more than a century,
but its inner workings were
a mystery until only recently.
Worms collectively undertaking
an underground exodus
seems especially unbelievable when you
consider how vulnerable this makes them.
So why is surfacing worth the risk?
Over the years, people have proposed
a number of imaginative hypotheses.
One was that worms were somehow
charmed by the noise,
like the rats from the medieval
Pied Piper legend.
Okay, sounds fun, but how would
the worms actually become bewitched?
Another hypothesis was that worm grunting
tickled their bodies,
so they emerged to end the aggravation.
Whimsical!
But worm grunting vibrates
the ground’s surface.
If worms were evading the vibrations,
wouldn't they burrow deeper instead?
Perhaps the most popular hypothesis was
that worm grunting mimicked falling rain
and the worms fled to avoid drowning.
In 2008, biologist Kenneth Catania
tested this hypothesis,
setting up three arenas filled with soil
and 300 individuals of the large species
of earthworm
found in the Florida Panhandle.
After an hour of rain,
water had pooled at the surface,
but only two earthworms emerged.
The rest remained buried and healthy.
So, unlike those containers,
this hypothesis just didn’t hold water.
Catania decided to explore
another route of inquiry.
In 1881, Charles Darwin published
his final work,
a bestseller that rivaled his
most well-known books at the time:
“The Formation of Vegetable Mould,
Through the Action of Worms,
with Observations on their Habits.”
Yes, it was literally called that—
and it was the culmination of 40 years
of earthworm investigations.
Within it, Darwin noted that worms
sometimes left their burrows
when the ground trembled
and mentioned an interesting hypothesis:
maybe they flee because they believe
they’re being pursued by moles.
Catania got to work testing
this hypothesis himself.
He found that Eastern moles had
astounding tracking abilities,
could eat their weight in worms every day,
and were abundant
in the Florida Panhandle.
When Catania released a single mole
into worm- and soil-filled arenas,
about 30% of the worms crawled
to the surface in the first hour—
a markedly different result
from the control and rain trials.
And when he recorded
the vibrations produced
by worm grunters and moles digging,
their frequencies
overlapped substantially.
This was it.
Over hundreds of thousands of years,
these earthworms evolved a behavior
that helped them escape a top predator.
Aboveground, they were immune
to the moles,
which usually stayed subterranean.
But then humans came along.
And, funnily enough, we aren’t even
the only ones
that take advantage of this behavior.
Herring gulls and wood turtles also
sometimes drum their feet on the earth
to summon worms.
So then why does this behavior persist?
Scientists think it’s beneficial
for a prey species
to maintain its adaptations
against a more frequent predator,
even if it makes it more vulnerable
to a rarer one.
Many insects, for example,
use flight to avoid predation.
But painted redstarts take
advantage of this:
they boldly flash their colorful tail
and wing feathers to elicit this response,
then catch the insects
as they try to fly away.
It seems the prey species’ response
remains
simply because it’s beneficial
most of the time.
For over a century, humans
in the southern US, the UK, and elsewhere
have been unknowingly exploiting
the worm’s escape response.
The current world record
for “most worms charmed”
was set by a 10-year-old
British girl in 2009.
Wiggling a fork in the ground
and hitting it with a stick,
she made 567 worms surface
in just 30 minutes.
Charming, really.
