Crustacean's claw may be
suited for battle
The club of the peacock mantis shrimp strikes
with such speed and force while staying intact
that scientists are trying to mimic its makeup
to protect troops in the line of fire.
June 08, 2012|By Eryn Brown, Los Angeles Times
The peacock mantis shrimp’s 2/10-inch-wide fist accelerates faster… (S. Baron )
Researchers have figured out how a tiny tropical crustacean packs an
outsized punch. And they are using that knowledge to engineer superdurable materials that could protect troops in the line of fire, among
other useful applications.
The peacock mantis shrimp, scientific name Odontodactylus scyllarus,
isn't actually a peacock, a mantis or a shrimp.
It's a stomatopod, a member of a group of aggressive ocean-dwellers
that use outsized appendages to smash, slash or spear their heavily
shelled prey.
How would you describe the mantis shrimp?
The mantis shrimp
It gets its name because of its colorful, shrimp-like appearance and
speedy, mantis-like "feeding strike," said David Kisailus, a professor of
chemical and environmental engineering at UC Riverside, who runs the
lab that is studying the animal.
And what a strike that is: When unleashed on a potential meal like a
crab or a snail, the peacock mantis shrimp's 2/10-inch-wide fist
accelerates faster than a .22-caliber bullet, reaching speeds of 45 mph
underwater and smacking its prey with 200 pounds of force.
The punch packs a double-wallop. By accelerating so quickly, the
animal's club actually boils the water surrounding it, creating bubbles
that implode upon prey, landing a second strike.
This pounding can penetrate mollusks' shells in a matter of seconds and
bust holes through glass. (The peacock mantis shrimps in Kisailus' lab
are housed in aquariums made of more-durable plastic.) But it doesn't
seem to damage the stomatopod.
Highlight the facts that you would you select to show the
mantis shrimp’s powerful strength.
"We were impressed that this guy can impact its prey tens of thousands
of times over a period of three to four months without breaking its own
hand," Kisailus said. "For decades people have studied snails as the
benchmark of impact resistance. Here's the stomatopod that eats those
guys for dinner."
To figure out how the peacock mantis shrimp pulls off this feat, Kisailus
and his team examined the creature's dactyl clubs
using electron microscopy, X-ray diffraction,
spectroscopy and computer simulations. They
discovered that the hammers' extraordinary strength
comes from a complex interaction between three distinct sections
within.
The outer part of the club, or the "impact region," is made of a
crystalline mineral material that can withstand compressive forces more
effectively than engineered ceramics forged at extreme temperatures.
The center, or "periodic region," is made of spiraling layers of sugarbased chitin fibers, reinforced by a different mineral material, that
absorb impact energy and prevent cracking.
Finally, the stomatopod depends on the "striated region," another layer
of chitin fibers that wraps around the entire club. Kisailus said these
fibers compress the minerals in the appendage, which also keeps
fractures from propagating.
The combination gives the peacock mantis shrimp its power, he said.
The results of the study were published online this week in the journal
Science.
What does the word club(s) mean in this selection?
The word club means
"This research is really cool," said Sheila Patek, a biologist at the
University of Massachusetts Amherst who studies mantis shrimp
mechanics. "They didn't just discover one thing — they discovered a
constellation of features that make this appendage so damage resistant."
Kisailus said he would like to develop materials that mimic the
components of the peacock mantis shrimp's super-tough fists, perhaps
for use in lighter, tougher types of body armor. (His work is funded in
part by the Air Force Office of Scientific Research.)
Engineers in Kisailus' laboratory have already started making composite
materials based on the tiny creature's biology, he said, forging
substances that are similar to the tissue in the periodic region and
forming them into sheets measuring about one foot square and less than
an inch thick.
Some of Kisailus' students took a few of the squares out to the desert
and fired at them with high-velocity rounds.
The squares cracked a bit but survived, with energy from the impact
dissipating laterally into the material.
The bullets were flattened.
Why does the author include this information at the end of
the article?
The author includes this information because