This cricket is about to be dinner.
New research reveals what makes a frog's tongue
such a formidable weapon.
This is Scientific American. I'm Lydia Chain.
Since the entire attack takes less
than a tenth of a second
the researchers set up high-speed
cameras to capture the action.
"Literally in the blink of an eye, the insect is gone
and it's only when we look at it in
slow-motion can we really see how the
tongue is unfurling from the mouth and
impacting the insect.
That's Alexis Noel at Georgia Tech.
Noel and her colleagues studied frog tongues
and the fluid mechanics of their spit
to understand how frogs slurp up their prey.
First, Noel studied the physical properties of the tongue.
It was so soft, Noel had to design
special equipment to get an accurate
softness measurement.
"It's even softer than brain tissue.
Even softer than a marshmallow."
That soft tongue comes in handy.
Prey sinks deep into the tongue's surface,
increasing contact for a good grip.
The softness also absorbs force
like a bungee cord so the frog can reel in
a cricket rather than giving it a yank
that might cause separation.
But it's the saliva that temporarily
glues the bug to a frog's tongue.
Frog tongues are like spit-saturated sponges
since their salivary glands
are inside the tongue.
Noel and her colleagues analyzed the
fluid properties of this saliva.
"So I scraped about 17 or 18 frog tongues."
Those spit samples revealed frog saliva is
a shear thinning fluid.
The saliva starts out viscous and sticky,
but when force is applied, it liquefies.
The force of hitting the insect
makes the spit splash up around the bug
"And it is able to penetrate all the tiny cracks
and crevices within the insect
increasing its contact area."
After that impact, the spit thickens again,
trapping the insect in the goo.
It's so sticky that the frog needs to
shove its eyeballs onto its tongue
in order to loosen the spit enough to swallow its morsel.
It's that combination of the soft tongue
and the sticky saliva
that lets frogs scoop up prey in an instant.
Of course not even super spit can help the frog
if it bites off more than it can chew.
For Scientific American, I'm Lydia Chain.