- How are fire ants like ketchup?
It's not a riddle, it's physics.
(light pop music)
Some materials are solids.
Some are liquids.
But some, like collections of fire ants,
have properties of both.
A study out of the Georgia
Institute of Technology
has found that groups of fire ants
have viscoelastic properties.
Like a soft-set JELLO, they
spring back when poked,
but can also ooze like a fluid.
This is actually the
latest ant-related research
out of Georgia Tech.
An associate professor from Tech's
School of Mechanical
Engineering, Dr. David Hu,
has been studying ant behavior
for nigh on ten years.
Why would a mechanical engineering expert
be so interested in insects?
It turns out that ants,
and particularly fire ants,
have an incredible
capacity to work together
in ways that mimic different materials.
They can use their own
bodies to build bridges,
and even form living
rafts when floods hit,
letting the colony float to safety.
So, working with the School of Physics'
Dr. Alberto Fernandes-Nieves,
Hu and the rest of the
team scientifically tested
the mechanical properties of fire ants,
both living and dead, using a rheometer.
This is a machine that studies
the behavior of soft materials.
Soft materials are
structurally interesting,
because they have both elastic
properties, like solids,
meaning that if you push them,
they snap back into shape,
and viscous properties, like liquids,
meaning that they can flow.
Rheometers test the combination,
the viscoelastic properties,
of stuff like plastic gels,
toothpaste, and baby food.
When you put a bunch of
fire ants in a rheometer,
they go with the flow.
Though they try to lock
together like a springy solid,
eventually they all let
go and flow like a liquid
to prevent injury.
You can also see this
when you gently smoosh
a ball of fire ants and watch
them puff back into place,
like a tasty snack cake of pain!
And, contrary-wise, when you drop a penny
into a tube of ants, and
watch them melt around it,
like a fondue pot of pain.
But it's nice to have
precise, rheological numbers
on this behavior.
That's all the ant material
science we've got time for now,
but be sure to check back at
now.howstuffworks.com every day
for more now, later.
