It’s the drag that helps the humble hagfish slime predators so quickly

Courtesy of University of Wisconsin, Madison.

The homely hagfish might look like just your average bottom
feeder, but they have a secret weapon: they can unleash a full
liter of sticky slime in less than one second. That slime can clog
the gills of a predatory shark, for instance, suffocating it.
Scientists are unsure just how the hagfish (affectionately known as
a “snot snake”) accomplishes this feat, but a
new paper
in the Journal of the Royal Society
Interface suggests that turbulent water flow (specifically, the
drag such turbulence produces) is an essential factor.

Scientists have been
studying hagfish slime
for years because it’s such an unusual
material. It’s not like mucus, which dries out and hardens over
time; hagfish slime stays slimy, giving it the consistency of
half-solidified gelatin. That’s due to long, thread-like fibers in
the slime, in addition to the proteins and sugars that make up
mucin, the other major component. Those fibers coil up into
“skeins” that resemble balls of yarn. When the hagfish lets loose
with a shot of slime, the skeins uncoil and combine with the salt
water, blowing up more than 10,000 times its original size.

Yet the
precise mechanism
for slime deployment is still poorly
understood, according to co-author Gaurav Chaudhary of the
University of Illinois, Urbana-Champaign. Recent research showed
that sea water is essential to the formation of the slime, and that
hagfish skeins can unravel spontaneously if ions in the sea water
mixes the adhesives that hold the fibrous threads together in
skeins. Chaudhary says that what’s missing in this earlier work is
taking the fast time scales into account. A 2014
, for instance, showed that any spontaneous unraveling of
the skeins would take several minutes—yet the hagfish deploys its
slime in about 0.4 seconds.

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Source: FS – All – Science – News
It’s the drag that helps the humble hagfish slime predators so quickly