Skip to main content

Baby Mantis Shrimp Don’t Pull Their Punches

Baby Mantis Shrimp Don’t Pull Their Punches

Mantis shrimp don’t need baby food. They start their life as ferocious predators who know how to throw a lethal punch.

A new study appearing April 29 in the Journal of Experimental Biology shows that larvae of the Philippine mantis shrimp (Gonodactylaceus falcatus) already display the ultra-fast movements for which these animals are known, even when they are smaller than a short grain of rice.

Their ultra-fast punching appendages measure less than 1 mm, and develop right when the larva exhausts its yolk reserves, moves away from its nest and out into the big wide sea. It immediately begins preying on organisms smaller than a grain of sand.

Although they accelerate their arms almost 100 times faster than a Formula One car, Philippine mantis shrimp larvae are slower than larger adults, which goes against the theoretical expectation that smaller is always faster.

“They’re producing amazing speeds and impressive accelerations relative to their body size, but they’re not as fast as adults,” said Jacob Harrison, a PhD candidate in biology at Duke University and lead author of the study.

Mantis shrimps achieve their ultra-fast movements through a tiny spring-actuated mechanism hidden in their punching appendage. A muscle contracts, deforming a tiny segment of their exoskeleton –the rigid cuticle that covers their body. This contraction allows elastic energy to be stored in the locked joint. Once the latch releases, the exoskeleton springs back into its natural position, violently propelling the appendage forward with ultra-fast speeds.

Engineering and physics models predict that smaller organisms, who have a smaller mass to displace, will be faster than larger, heavier, organisms. Mantis shrimp larvae show that biology doesn’t always follow the theory.

“Theoretically, they should be producing the highest acceleration,” said Harrison, “but we don’t find that.”

Harrison explains that this discrepancy may be due to multiple factors. The larvae muscles may be too small to effectively load a very stiff spring, or the water resistance at their small size may be too high for their punches to reach the speed that larger individuals reach, among other possibilities.

“There are limitations to these spring and latch structures that we don’t fully understand,” said Harrison. “But whenever biology moves away from theoretical models it highlights some pretty interesting areas for us to learn.”

Mantis shrimp larvae are an interesting system not only due to their small size, but also due to their color, or lack thereof.

Adult mantis shrimps have opaque exoskeletons, rendering the inner working of their spring-latch mechanisms impossible to observe in action. The exoskeleton of larvae, however, is much thinner and fully transparent, allowing researchers to see precisely how these animals manage to store so much elastic energy in their tiny appendages simply by watching them through a microscope.

“One of the trickiest parts of researching spring-actuated mechanisms is that a lot of those elements are working inside the animal. We can look outside of the animal and see the behavior, measure the kinematics, dissect the animal, and say the mechanism looks like it works like this, but there are always levels of assumption,” said Harrison.

“(Transparency) sets up larval mantis shrimps as systems where we can look at how each of these elements work in concert together,” said Harrison. “It removes assumptions and allows us to understand it on a finer scale.”

Larval mantis shrimps are therefore doubly interesting. They highlight discrepancies between physics and biology, and also offer a true window into a better understanding of the mechanism behind ultra-fast movements.

“When something doesn’t match your predictions, the first gut reaction is always to be incredibly frustrated, but this is actually what highlights new areas of research,” said Harrison.

This work was supported by the Company of Biologists Traveling Fellowship (JEBTF181185), by the National Science Foundation (NSF IOS 1439850 and NSF EPSCoR RII 455 1738567), by the Office of Naval Research (N00014-19-1-2035 and N00014-454 17-1-2062), and by the University of Hawai’i at Mānoa. This material is based upon work supported by, or in part by, the U.S. Army Research Laboratory and the U.S. Army Research Office under contract/grant number W911NF-15-1-058.

CITATION: “Scaling and development of elastic mechanisms: the tiny strikes of larval mantis shrimp,” J. S. Harrison, M. L. Porter, M. J. McHenry, H. E. Robinson, S. N. Patek. Journal of Experimental Biology, April 29, 2021. DOI: 10.1242/jeb.235465



from ScienceBlog.com https://ift.tt/3e6x3jd
Labels:

Comments

Post a Comment

Popular posts from this blog

Wiggling worms suggest link between vitamin B12 and Alzheimer’s

Worms don’t wiggle when they have Alzheimer’s disease. Yet something helped worms with the disease hold onto their wiggle in Professor Jessica Tanis’s lab at the University of Delaware. In solving the mystery, Tanis and her team have yielded new clues into the potential impact of diet on Alzheimer’s, the dreaded degenerative brain disease afflicting more than 6 million Americans. A few years ago, Tanis and her team began investigating factors affecting the onset and progression of Alzheimer’s disease. They were doing genetic research with  C. elegans , a tiny soil-dwelling worm that is the subject of numerous studies. Expression of amyloid beta, a toxic protein implicated in Alzheimer’s disease, paralyzes worms within 36 hours after they reach adulthood. While the worms in one petri dish in Tanis’s lab were rendered completely immobile, the worms of the same age in the adjacent petri dish still had their wiggle, documented as “body bends,” by the scientists. “It was an observa...
Post a Comment
Read more

‘Massive-scale mobilization’ necessary for addressing climate change, scientists say

A year after a global coalition of more than 11,000 scientists declared a climate emergency, Oregon State University researchers who initiated the declaration released an update today that points to a handful of hopeful signs, but shares continued alarm regarding an overall lack of progress in addressing climate risks. “Young people in more than 3,500 locations around the world have organized to push for urgent action,” said Oregon State University’s William Ripple, who co-authored “The Climate Emergency: 2020 in Review,” published today in Scientific American. “And the Black Lives Matter movement has elevated social injustice and equality to the top of our consciousness. “Rapid progress in each of the climate action steps we outline is possible if framed from the outset in the context of climate justice – climate change is a deeply moral issue. We desperately need those who face the most severe climate risks to help shape the response.” One year ago, Ripple, distinguished profess...
Post a Comment
Read more

Ancient Shell Sounds

Abandoned at the mouth of your shelter you quivered apprehensively at our approach, crying out to be held as we proclaimed the exception of your discovery. Sighing wearily as we consigned you to the dusty silence of our archives. But now When I hold you in my hands, I see the face of your purposefully speckled complexion. When I lift you to my ear, I hear the sound of an ancient sea lapping at your shores. When I place you at my lips, I feel the heartbeat of your creator pulsing to my breath. I close my eyes, as you call out to all that you have lost. The shell that was recovered from the Marsoulas cave in the Pyrenees of France (Image Credit: C. Fritz, Muséum d’Histoire naturelle de Toulouse). This poem is inspired by recent research , which has discovered that a large seashell that sat in a French museum for decades is actually a musical instrument used around 18,000 years ago. In 1931, researchers working in southern France unearthed a large seashell at the entr...
Post a Comment
Read more