shell

Weekend Diversion: An 8-bit mashup, reimagined

esiegel — Sun, 05 May 2013 08:43:38 +0000

Weekend Diversion: An 8-bit mashup, reimagined

"I don't understand how super mario can smash blocks with his head but dies when he touches a turtle." -Unknown

The past few weekends have been far too serious around the internet, and it's time to kick back and enjoy something nice and simple. I'd like to introduce you to the little-known indie band The Mountain Goats, who, along with Kaki King, sing a delightful song about feeling trapped and being rescued, called

Thank You Mario But Our Princess Is In Another Castle.

Of course, those of you who remember your old nintendo cartridges will know exactly where the song title comes from.

Image credit: J.A. Laraque of http://obsoletegamer.com/.

From the original Super Mario Bros., of course! Stomping goombas and kicking koopas was part of the joy of growing up in the 1980s. But a few years later, a different type of turtle-shelled cartoon took hold across my childhood landscape, and one couldn't help but wonder if Mario's turtle-stomping history would catch up with him?

Images credit: mudkipz master of http://www.neoseeker.com/ (L) and Tim of http://oldschool.tblog.com/ (R).

That's right: what if the Teenage Mutant Ninja Turtles came back for revenge on Mario and Luigi? It could happen, as predicted by the internet!

Image credit: Markham Asylum of http://www.deltaattack.com/.

But it was recently pointed out to me that there exists an amazing fan artist -- jpzilla of deviantART -- who had done a little nintendo-based imaginings doing a Daily Doodle.

Image credit: J.P. Perez's Daily Doodle #2.

There were the Ninja Turtles, which appeared above as just his second drawing, and this one of a young Mario Bros., which came a couple of months later.

Image credit: J.P. Perez DD #74, via his art page: https://www.facebook.com/ArtByJP.

A few weeks later, he began a brief mini-series based on the theme of Mario, the Ninja Turtles, and revenge! I think it's brilliant.

Image credit: J.P. Perez's Daily Doodle #102.

This first one was titled Mario Learns The Meaning of Karma, and was followed by REVENGE!!

Image credit: J.P. Perez's Daily Doodle #103.

Which in turn was followed by JUSTICE!!!

Image credit: J.P. Perez's Daily Doodle #104.

And finally, the series culminated with FOUL PLAY!!!!!

Image credit: J.P. Perez's Daily Doodle #105. Nice touch with the slippers.

You can check out his facebook page, his deviantART page, and also his tumblr for more information and pictures. I hope this series amused you as much as it did me, and I hope you have a great rest-of-your-weekend, no matter what you're doing or where you are!

esiegel Sun, 05/05/2013 - 04:43

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Random Stuff

Art

castle

J.P. Perez

those were really funny and awesome. The title 8 bit mashup is very apt for this post. Anyway, the whole idea of bringing in Ninja turtles in to mario is too good

Well then.
Everything's under control.

Wow, thanks for featuring my stuff! I accidentally ran into this post and was very surprised and delighted! Thanks!!

Strength in Nature

dr. dolittle — Thu, 20 Sep 2012 18:09:42 +0000

Strength in Nature

This is a must-see special from NOVA highlighting nature's secret to creating very strong things: like the beak of a toucan, an abalone shell and a spider's web. It aired last night on PBS (premiered Jan 2011) and I found myself glued to the TV. Scientists are working hard to try to re-create some of nature's amazing strength to help improve existing technologies. One that I found amazing: scientists have been able to create genetically modified sheep to mass produce spider silk, which is reportedly stronger than kevlar!

Watch Making Stuff: Stronger on PBS. See more from NOVA.

If you cannot see the embedded video, click here to be taken to the website.

dr. dolittle Thu, 09/20/2012 - 14:09

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Fossil Shell Preserves Signs of a Prehistoric Tug-of-War

laelaps — Thu, 15 Apr 2010 10:44:21 +0000

Fossil Shell Preserves Signs of a Prehistoric Tug-of-War

Top of the encrusted surface of a brachiopod shell, showing the "war" between an edrioasteroid (star-shaped organism at center) and a fast-growing bryozoan colony. From Sprinkle and Rodgers 2010.

Back in the early days of paleontology, when the meaning and origin of fossils was still in doubt, some naturalists believed that the shells, shark teeth, and other petrified curiosities were attempts by the rock to imitate life. Fossils were not true vestiges of history, it was believed, but instead the product of some "plastic virtue" suffused throughout the non-living Creation. As naturalists began to study fossils more closely, however, they realized that the ancient shells showed signs of growth just like their counterparts along the seashore. Fossils were not crude imitations of life. Instead they were the traces of long-deceased organisms which had been transformed, and while it is easy to take this fact for granted today there are quite a few stunning specimens which beautifully reaffirm that paleontology is the study of ancient life.

As explained by paleontologists James Sprinkle and Jeri Rodgers in the Journal of Paleontology, between about 300-315 million years ago what is now Brown County in north-central Texas was covered by a shallow bay or tidal channel. Bivalve shells, bits of trilobite, shark teeth, crinoids, and other such fossils have been found here, including a large number of brachiopods. Though they might superficially look like just another kind of mollusc, brachiopods belonged to an entirely different phylum, one that flourished during the past but has been reduced to just a handful of species today. You can tell them apart from mollusc shells because brachiopods had upper and lower shells which were hinged at the back (giving some the appearance of an oil-lamp, hence their common name "lamp shells"). Given the abundance of these fossils it is easy to simply collect them and store them away, but a closer look at one specimen in particular documented a years-long struggle between two organisms.

Encrusted on the lower shell of the brachiopod Composita were two organisms: a colony of tiny marine invertebrates called bryozoans and a single individual of a kind of echinoderm called an edrioasteroid, with the bryozoans creating an almost complete ring around the starfish-like echinoderm. Both were trying to eek out a living on the brachiopod shell, and neither was giving up a millimeter of space.

From what Sprinkle and Rodgers were able to tell from the fossil, the sequence of events probably went as follows. The brachiopod which the shell represents grew for a number of years, but eventually died. At this point the two valves of the shell may have become separated, providing prime real-estate for the encrusting invertebrates which lived in the shallow Carboniferous bay. The echinoderm was the first to latch on, gradually growing as it sat on the shell, but sometime later a bryozoan larvae also took up residence there. Since it could reproduce asexually, it soon began creating a colony of other bryozoans which eventually came into contact with the echinoderm.

Once the different invertebrates made first contact, the organisms began to struggle with each other for shell space. The bryozoans continued to grow over the available parts of the shell, surrounding the echinoderm, but they could not overtake it. The echinoderm, on the other hand (or tube foot, if you like), held back the bryozoan colony but could not continue to grow outward. Just how the echnioderm held its ground is unknown, perhaps it had some kind of physical or chemical defense to keep the bryozoans from building up too high along the margins of its living space, but regardless of the weapons used in the struggle Sprinkle and Rodgers describe how the conflict was probably brought to an end:

The stalemate in the edrioasteroid/bryozoan war for living space continued for a while longer as the bryozoan almost completely surrounded the edrioasteroid. By then, both competing organisms had grown to sexual maturity and had probably reproduced. Finally a major storm or flood event buried and killed both organisms, breaking off the bryozoan's projections at this or a later time.

This tug-of-war between marine invertebrates would only have been detectable with the passage of time. Like the growth of the brachiopod itself, it occurred at a rate that would have been nearly imperceptible to us, but it was a dire struggle nonetheless.

Sprinkle, J., & Rodgers, J. (2010). Competition between a Pennsylvanian (Late Carboniferous) Edrioasteroid and a Bryozoan for Living Space on a Brachiopod Journal of Paleontology, 84 (2), 356-359 DOI: 10.1666/09-089R.1

laelaps Thu, 04/15/2010 - 06:44

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Timeless...literally and figuratively.

DNA from the largest bird ever sequenced from fossil eggshells

edyong — Tue, 09 Mar 2010 18:00:31 +0000

DNA from the largest bird ever sequenced from fossil eggshells

Even extinction and the passing of millennia are no barriers to clever geneticists. In the past few years, scientists have managed to sequence the complete genome of a prehistoric human and produced "first drafts" of the mammoth and Neanderthal genomes. More controversially, some groups have even recovered DNA from dinosaurs. Now, a variety of extinct birds join the ancient DNA club including the largest that ever lived - Aepyornis, the elephant bird.

In a first for palaeontology, Charlotte Oskam from Murdoch University, Perth, extracted DNA from 18 fossil eggshells, either directly excavated or taken from museum collections. Some came from long-deceased members of living species including the emu, an owl and a duck. Others belonged to extinct species including Madagascar's 3-metre tall elephant bird and the giants moas of New Zealand. A few of these specimens are just a few centuries old, but the oldest came from an emu that lived 19,000 years ago.

It turns out that bird eggshells are an excellent source of ancient DNA. They're made of a protein matrix that is loaded with DNA and surrounded by crystals of calcium carbonate. The structure shelters the DNA and acts as a barrier to oxygen and water, two of the major contributors to DNA damage. Eggshells also stop microbes from growing and it seems that ancient ones still do the same. Oskam found that the fossil shells had around 125 times less bacterial DNA than bones of the same species did.

This is important - bacteria are a major problem for attempts to extract ancient DNA and they force scientists to search for uncontaminated sources, like frozen hair. Eggshells, it seems, provide similarly bacteria-free samples. Still, Oskam's team took every precaution to prevent contamination. They used clean rooms and many control samples. Many of their sequences, like those of Aepyornis, were checked by two independent laboratories.

The Aepyornis sequences are particularly encouraging because many scientists have previously tried to extract DNA from the bones of this giant and failed. Eggshells seem like a more promising source and it certainly helps that the eggs of many of these giant species were massive and thick. But Oskam did also recover DNA from a fossil duck egg, which suggests that it should be possible to sequence the genes of even small extinct birds, like the dodo.

So far, the team have proved that they can extract the DNA. It's what they do with it that counts. It's worth remembering that fossil eggshells have already helped palaeontologists to date the remains of ancient birds, and reconstruct their diets and lifestyles. Some even clue us into the artistic traditions of our own ancestors.

Oskam is now analysing around 400 pieces from sites around New Zealand to understand how humans interacted with the moas and how our zealous hunting drove them to extinction. There were several different species of moa that are difficult to tell apart - egg DNA could help Oskam to do just that. The same technique could be used to study the last days of other extinct birds with interesting evolutionary histories, including the great auk, Haast's eagle and that poster child for extinction, the dodo.

Mike Bunce, who led the study, is keen to try and release ancient DNA from eggshells all around the world. "Given frozen environments preserve DNA 'better', we are very keen to examine any eggshell finds from 'old' sediments, such as seabird nesting sites, in the Arctic and Antarctic," he says. And the door should now be open for other researchers to do the same. After all, in finding out how to extract DNA from eggshells, Oskam tested a variety of methods to develop the most efficient possible protocol.

Still, it's clear that the technique has limitations. Oskam tried to extract DNA from the 50,000-year-old shell of Genyornis, a giant Australian bird that lived in a very hot climate. She failed. And as Bunce clearly stresses, "This is not a technique that is applicable to fossil dinosaur eggs."

Update: That hasn't stopped the idiotic headline writers to London's Metro newspaper from claiming that "Jurassic Park has just taken a giant T-Rex-sized step toward becoming reality after ancient DNA from long-extinct creatures was successfully extracted." Amusingly, the claim that dinsoaur DNA has been rebuilt is technically true given that birds are living dinosaurs. And if the subeditor who wrote the headline and standfirst and chose the picture actually knew that, I'd be surprised.

Reference: Oskam, C., Haile, J., McLay, E., Rigby, P., Allentoft, M., Olsen, M., Bengtsson, C., Miller, G., Schwenninger, J., Jacomb, C., Walter, R., Baynes, A., Dortch, J., Parker-Pearson, M., Gilbert, M., Holdaway, R., Willerslev, E., & Bunce, M. (2010). Fossil avian eggshell preserves ancient DNA Proceedings of the Royal Society B: Biological Sciences DOI: 10.1098/rspb.2009.2019

More on ancient DNA:

edyong Tue, 03/09/2010 - 13:00

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An 60,000-year old artistic movement recorded in ostrich egg shells

edyong — Mon, 01 Mar 2010 14:00:18 +0000

An 60,000-year old artistic movement recorded in ostrich egg shells

Souvenir shops in South Africa are full of lamps made out of ostrich eggs. The eggs are so big and strong that you can carve and cut intricate designs into their shells. The egg's contents are emptied through a hole and a bulb can be inserted instead, casting pretty shadows on walls and ceilings. The results are a big draw for modern tourists, but ostrich eggs have a long history of being used as art in South Africa. The latest finds show that people were carvings symbolic patterns into these eggs as early as 60,000 years ago.

Pierre-Jean Texier from the University of Bordeaux discovered a set of 270 eggshell fragments from Howieson Poort Shelter, a South African cave that has been a rich source of archaeological finds. Judging by their patterns, the fragments must have come from at least 25 separate eggs, although probably many more.

Texier says that the sheer number is "exceptional in prehistory". Their unprecedented diversity and etched patterns provide some of the best evidence yet for a prehistoric artistic tradition. While previous digs have thrown up piecemeal examples of symbolic art, Texier's finds allow him to compare patterns across individual pieces, to get a feel of the entire movement, rather than the work of an individual.

As you might expect, the millennia haven't been too kind to the shells but even so, their etchings are still well preserved and Texier even managed to fit some of the pieces together. Despite the variety of fragments, their patterns fall into a very limited set of motifs produced in the same way - a hatched band like a railway track, parallel(ish) lines, intersecting lines, and cross-hatching. It's possible that, once assembled, these elements would have combined into a more complex artistic whole but Texier notes that he has never found a piece with more than one motif on it.

Much like any other artistic movement, the shell designs had rules that everyone abided by, but also room for some stylistic latitude. There were four main styles but each had some wiggle room in their execution. The railway track, for example, had lines of different lengths and intersection angles. While some fragments had just one track, others had two or three.

These traditions also seem to have risen into fashion and fallen out of them again. The railway track motif only turns up in the lower parts of the cave and not in eggshells from the upper reaches. Go further up, and it's the parallel lines motif that dominates. To Texier, the shell motifs are evidence that these prehistoric humans were more than capable of symbolic thought, of using patterns to transform ordinary items into specific and unique ones.

Today, hunter-gatherers in the Kalahari still collect ostrich eggs, for food, as beads, or as water containers. They puncture a small hole in the top of the egg, empty their contents and fill them with water. Texier says, "Some Bushmen groups, like the !Kung, use a graphic and schematic tradition to communicate collective identities as well as individual ones." He thinks that the prehistoric hunter-gatherers may have used the eggs for a similar purpose. Their engravings may have been used to intentionally mark ostrich eggshell containers and some of the fragments show signs of forced entry, typical of modern egg-based water containers. To Texier, they were "elements of a collective and complex social life", signs of a modern human intelligence operating tens of thousands of years ago.

Christopher Henshilwood, another anthropologist working in South Africa, was also impressed. "Based on sheer numbers the evidence for deliberate decoration and symbol use is compelling." He adds, "Perhaps the greatest challenge still is in explaining why the tradition of engraving appears to... appear, disappear and then reappear at different times and places."

Several years ago, Henshilwood found a different piece of abstract art at another South Africa cave called Blombos. It was a slab of ochre, also covered in geometric carvings and dating back to 70,000 years ago. "Is there really a connection betweeen the engraving traditions at 100 ka, 75 ka, 60 ka and those in the Later Stone Age?" he asks. "And why are engraved ostrich eggshells and ochre only found at some Middle Stone Age sites and not others?"

Reference: Texier, P., Porraz, G., Parkington, J., Rigaud, J., Poggenpoel, C., Miller, C., Tribolo, C., Cartwright, C., Coudenneau, A., Klein, R., Steele, T., & Verna, C. (2010). A Howiesons Poort tradition of engraving ostrich eggshell containers dated to 60,000 years ago at Diepkloof Rock Shelter, South Africa Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0913047107

More on art and archaeology: Prehistoric carving is oldest known figurative art

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edyong Mon, 03/01/2010 - 09:00

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Ok, so I get that they carved the ostrich egg shells, and the stylistic changes, and all that, and how important it is for our understanding of our culture... but I think you are missing the far more mind-boggling question:

Where did they plug in the lampcords?

I just love to imagine those artists of 60,000 years ago. How much have human beings really changed since then? It's such a short time really.

Could these eggs and their "decorations" also predate the basic early writing on amphorae used to store grain and identify its owners in the fertile crescent of the Middle East? Is it pure art or did it serve a functional purpose?

Could these eggs and their "decorations" also predate the basic early writing on amphorae used to store grain and identify its owners in the fertile crescent of the Middle East?

I think the earliest records of grain storage of any sort only went back to about 11,000 BCE - much, much younger than this ostrich egg art.

Not writing, rudimentary counting, another type of record akin to 'counting sticks', and the sacred red ochre slab - Hunter-gather clan portable records.

Doubt it's simple abstract artwork. Early humans were acting with intent, driven by harsh conditions after a long period of paleoclimate chaos. Ancient South Africans were dispersing, migrating northward. Climate change was afoot, cooling and drying with the onset of glaciation.

http://www.esd.ornl.gov/projects/qen/nercAFRICA.html

>How much have human beings really changed since then? It's such a short time really.

Well, it's a short time-frame....if you are a rock.

On potential for ancient uses for these shells: probably water storage, but maybe for seed and nut transport and storage as well.

Before grain cultivation 7-10K years ago, wild grains may have been collected, stored and crudely prepared as a mash, but they wouldn't have been a dietary rarity because ancient grains heads were low yield and had limited very geographical range. Moreover, ancient human lacked the technical innovations necessary for large-scale grain harvesting: threshing, winnowing, and grinding. Grinding broke down grain cells walls and liberated nutrients that would be otherwise unaccessible to gut mechanical or chemical digestion.

Domestication of grains induced dramatic changes in diet-induced cellular metabolism in humans. Just as the ancient practice of cooking meat and ground roots in simple hearths have been hypothesized to have altered brain size and anatomic features at a much earlier time (long before 60 KYA), the addition of cooked domesticated grains to the human diet dramatically changed gut microbiota and energy supply, with concurrent shift in secretory and immune function, by introducing an ample supply of fast-acting energy in short-chain fatty acids and starch.

These caloric benefits came with a cost: anti-nutrients, grain components like phytates, lectins (wheat gluten) and alkylrescorcinols (inflammatory agents).

The timing of animal and grain domestication with sedentary (non-migrating) lifestyle in permanent settlements, and attendant population and technological growth is critical for understanding emergence of many human pathogens and chronic diseases.

It's a very, very interesting story. That's what can happen in just 10,000 years time.

A few comments: the site's actually called Diepkloof, and the engrave ostrich eggshell fragment were found in layers attributed to the Howiesons Poort cultural tradition, which is documented in only a few of the site's archaeological layers over a period of ca. 10,000 years. This raises the questions of why these behaviors (both use of ostrich eggs as containers, and their decoration) appear so comparatively fleeting, especially since it's generally argued they represent evidence for the 'modern' behavior critical to H. sapiens success. I discuss some of this here:
http://averyremoteperiodindeed.blogspot.com/2010/03/60000-year-old-deco…

Three-layered shell of deep-sea snail could inspire next-gen body armour

edyong — Tue, 19 Jan 2010 08:44:05 +0000

Three-layered shell of deep-sea snail could inspire next-gen body armour

Deep beneath the ocean's surface lie the "black smokers", undersea chimneys channelling superheated water from below the Earth's crust. Completely devoid of sunlight, they are some of the most extreme environments on the planet. Any creature that can survive their highly acidic water, scorching temperatures and crushing pressures still has to contend with assaults from predatory crabs. What better place, then, to look for the next generation of body armour technology?

The scaly-foot gastropod (Crysomalion squamiferum) was discovered just 9 years ago at an Indian black smoker and it may have one of the most effective animal armours so far discovered. Its shell is a composite, made of three layers, each with different properties and made of different minerals. Together, they form a structure that's completely unlike any known armour, whether natural or man-made. It can protect the animal from the searing heat of its habitat, stop its precious minerals from dissolving away in the acidic water and resist the crushing, penetrating, peeling claw-attacks of predatory crabs.

Animals have been protecting themselves with armour long before humans starting shaping steel and Kevlar. To create a protective covering, human designers must account for a mind-boggling array of physical traits including thickness, geometry, strength, elasticity and more. But evolution can take all of those factors into account without the guiding hand of a designer, putting thousands of structures through the test of natural selection and weeding out the best combinations. The results are the culmination of millions of years of research and development and they are striking in their effectiveness.

Haimin Yao from MIT works in the lab of Catherine Ortiz, a group that has been studying the defences of animals including sea urchins, chitons, a group of marine molluscs, to the Senegal bichir, a type of armoured fish.

Yao discovered the secrets behind the snail's shell by slicing through it in cross-sections and studying its structure at a nanometre level. He even attacked it with a diamond-tipped probe, to simulate the crushing attacks of the crabs that frequent the black smokers. Using this data, Yao created a virtual simulation of the shell and put it through a digital crash-test, crab claws and all.

The outer layer is the thinnest but also the toughest. It's rich in iron sulphide nanoparticles and the snail is the only animal known to use these minerals to build a shell. There's good reason for this - the water around the black smokers is absolutely teeming with iron sulphides, so the snail has plenty of mortar for its construction needs.

When crushed by a crab claw, the outer layer cracks but that's all part of the plan. The cracks are tiny and jagged. They dissipate the energy from the attack and prevent larger cracks from forming - those could cause the entire shell to shatter. The tough iron minerals can also grind and erode the crab's claw - it's a defence that also weakens the attacker's weapon.

The middle layer is organic with no minerals to speak of. It's much thicker than the other one but it's also soft and spongy. It also helps to absorb the force from the crab's blows, dissipating their energy before it reaches the inner layer. The boundary between the outer and middle layers is wavy rather than flat, which reduces the risk that the two will simply disconnect and slide off one another.

Only when you get to the inner layer do you find calcium carbonate, the building material that most snails use to construct their shells. In the acidic water of a black smoker, an uncovered calcium carbonate shell would rapidly dissolve away, leaving behind a naked and vulnerable snail. Again, the three-layer armour comes into its own, with the outer and middle layers protecting the inner one from the acidic water, and from the frequent bursts of intense heat.

The rigid inner layer isn't useless though. It adds structural support and prevents the shell from bending. That foils one of the crab's main tactics - shoving its claw into the shell's opening and peeling off small chunks until it can reach the animal inside.

Yao says that this multi-layered armour could help to inspire the next generation of man-made defences. Potential uses aren't just limited to armour for people or vehicles, but sporting equipment or coverings for pipelines that are frequently hit by rocks. In particular, he's intrigued by the snail's use of an outer layer of iron nanoparticles as a sacrificial structure, designed to trap cracks and dissipate energy. That's an original idea as far as human design goes and one that the group will be eagerly following up.

Reference: Yao et al. 2010. Protection mechanisms of the iron-plated armor of a deep-sea hydrothermal vent gastropod. PNAS http://dx.doi.org/10.1073/pnas.0912988107

More on biological materials science:

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edyong Tue, 01/19/2010 - 03:44

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So we drag these snails out of the depths of the ocean and murder them in order to learn how better to murder fellow members of our species.

How very human of us.

Allow me to explain the concept of *armour*. It is a thing that stops pointy things from making you go ow. Clearer?

And if you're trying to murder people USING body armour, you're doing it wrong.

Great post, Ed!
I was wondering: do you know how the snail protects its fleshy parts during such processes as feeding, traveling and mating - or can it easily handle short-term exposures of its more vulnerable sides to the acidic water and high heat of its environment?

Just don't beat anyone to death with a giant snail...

That's seriously fascinating, though. Remind me to email this to the next person who asks what practical use the study of nature is...

Great post as always, and thanks to Mad the Swine I am now trying to work out how you could even *use* body armour as a weapon short of hitting someone over the head with it. They should add it to cluedo: "Reverand Green, in the ballroom, with the full suit of body armour" :)

Well exactly. I've got (a) just bludgeoning people with it, (b) smothering or (c) stabbing *yourself* with a bladed weapon so that it bounces off into someone else.

As I said, doing it wrong.

Ferris - sadly no. Didn't see any reference to this in the paper (but it *was* incredibly dense, so I may have missed something).

Tracey - try The Gecko's Foot too. Awesome book on biomimetics.

How about (d), you give it to a US soldier or Blackwater mercenary, who then is able to last longer under fire and so rack up a higher body count.

Any improvement in the technology of warfare leads to more dead people. Better armor just shifts the casualties to the other side.

@mad the swine

Unfortunately, even basic science research such as this can result in uses not intended or even foreseen by the researchers involved. People do not typically begin careers in marine biology with the aspiration of killing people, and it is rather asinine of you to focus on this singular application when other uses (such as sporting equipment) were mentioned and many more can easily be conceived. Your inability to look beyond your social/political opinions* to appreciate this study of a truly remarkable creature or to simply move along to a different blog belies your prejudices - and your immaturity.

* Guess what, I'm vegan, and I don't believe war is the answer, either.

@Ed Yong

As always, a fascinating post.

Nice post.

Seems like crushable styrofoam, the kind you find in bicycle helmets, operates on a similar principle.

Sweet. Unfortunate use of the word 'design' in the figure though.

"So we drag these snails out of the depths of the ocean and murder them in order to learn how better to murder fellow members of our species.

How very human of us."

I think, what MAD THE SWINE is trying to imply is that protecting ourselves largely involve MURDERING as well. Well, we can very well see that defense never existed without offense. Nevertheless, this issue rocks! Keep this up!

@ Tracey:

Speaking of gecko feet, check out this talk on TED.

http://www.ted.com/talks/lang/eng/robert_full_learning_from_the_gecko_s…

and

http://www.ted.com/talks/robert_full_on_engineering_and_evolution.html

Re: Comment 1 - there's a pervasive belief that any research that is funded by or used by the military is inherently evil. The line of thought for armor goes: "If US soldiers get better body armor, then they are a more effective fighting force and so the government will be more likely to use them, leading to more war. Therefore any aid to military = more war = evil.
Call me crazy, but I think of research that reduces death and promotes health to be a good thing, regardless of who is helped by it.

Great post....and i'll have to check that biomimetics book.

can we conceive of shells for laptops or impact zones for cars/trains/planes from this information, or are we simply relegated to killing people with it *because* that is a foreseeable option? ;) rock on, good article.

The improvements in body armor from this research do not address momentum-transfer trauma caused by stopping the heavier, more energetic round. the Marine or soldier who is struck may survive on the battlefield but then must endure unknown physical effects for years and the all too well-known psychological trauma. Also any moderate advance in body armor will not defeat any round that will be introduced that utilizes enhanced incendiary/reactive chemical components. In fact this may well spur the introduction of these component based rounds into general infantry use. This would be counterproductive and increase suffering even beyond the use of Willy Pete white phosphorus.

Its shell is a composite, made of three layers, each with different properties and made of different minerals. Together, they form a structure that's completely unlike any known armour, whether natural or man-made.

If the uniqueness is in the use of different layers with very different properties rather than the exact materials used, then this isn't really unique. Modern tank armour has made use of similar layering using various different steels, ceramics, dead space, depleted uranium slabs and polymers (like Kevlar spall linings) for the last 30 years or so. Most modern tank armours are of layered construction. The processes they inflict on penetrators are similar to what's described above (the outer iron sulphide later sounds like it works like the ceramics in modern armours, including some body armours). And with all due respect to the gastropod, a crab claw is not a 10kg tungsten bolt travelling a kilometre and a half per second. Not to say there's nought to be learned from Mother Nature here, but it does seem they're being a bit excitable.

Now, has anyone put that Crysomalion squamiferum up against a hungry Odontodactylus scyllarus for a real test?

Great post.

Small point, Ed. You say: "But evolution can take all of those factors into account without the guiding hand of a designer, putting thousands of structures through the test of natural selection and weeding out the best combinations." I think you might mean, either, 'ferreting out' or 'weeding out weak combinations, and retaining the best ones'.

Do the snails repair their shell after being attacked? If they did, studying the repair mechanism might provide some pretty interesting insights.

If they don't, is that because they don't get attacked often? I'd assume that a snail with a weakened shell would be pretty vulnerable, even if it did survive the initial attack.

This just prove Darwin correct again on the survival of the fittest natural selection dogma.

Another Darwinian triumph. I think this is exactly what Darwin noticed with the parallelism of environment and the development of features to adapt to it.

Well only religious idiots wouldn't believe Darwin. Even God believes in Darwin.

How the turtle got its shell through skeletal shifts and muscular origami

edyong — Thu, 09 Jul 2009 14:00:57 +0000

How the turtle got its shell through skeletal shifts and muscular origami

The turtle's shell provides it with a formidable defence and one that is unique in the animal world. No other animal has a structure quite like it, and the bizarre nature of the turtle's anatomy also applies to the skeleton and muscles lying inside its bony armour.

The shell itself is made from broadened and flattened ribs, fused to parts of the turtle's backbone (so that unlike in cartoons, you couldn't pull a turtle out of its shell). The shoulder blades sit underneath this bony case, effectively lying within the turtle's ribcage. In all other back-boned animals, whose shoulder blades sit outside their ribs (think of your own back for a start). The turtle's torso muscles are even more bizarrely arranged.

This body plan - and particularly the odd location of the shoulder blades - is so radically different to that of all other back-boned animals that biologists have struggled to explain how it could have arisen gradually from the standard model, or what the intermediate ancestors might have looked like. Enter Hiroshi Nagashima from the RIKEN Center; he has found some answers by studying how the embryos of the Chinese soft-shelled turtle (Pelodiscus sinensis) shift from the standard body plan of other vertebrates to the bizarre configuration of adult turtles.

By comparing the embryos to those of mice and chickens, Nagashima showed that all three species start off with a shared pattern that their last common ancestor probably shared. It is only later that the turtle does something different, starting of a sequence of muscular origami that distorts its body design into the adult version.

Initially, the embryos of all three species have shoulder blades that sit outside the ribs. In the mouse and chicken, the blade starts to grow backwards, extending down the trunk across the developing ribs. The ribs themselves have extended down the embryos' flanks and are surrounded by a layer of muscle called the muscle plate (or myotome). These elements - the ribs, the shoulder blade and the muscle plate - stay in much the same formation as the animals grow into adults.

In the turtle, early embryos share the basic plan as those of mice and chickens, but there are subtle differences. The shoulder blade is positioned further forward and the ribs themselves are much shorter, never reaching down into the embryo's flanks. As it grows, things change dramatically.

The muscle plate in the lower half of the turtle's body folds inwards along a line that runs down the turtle's body. This line will eventually form the edge of the shell and it's called the carapacial ridge. Meanwhile, the second pair of ribs (r2 in the image below) grows outwards and swing forwards over the shoulder blade (sc in the image below). A similar thing happens over the animal's hips. These two crucial events - the folding of the muscle plate and the growth of the second ribs - bring the shoulder blade within the confines of the ribcage. Both steps are possible because the turtle's ribs stop growing early on in its development and no one yet know why this happens.

The muscle that connects the shoulder blade to the second pair of ribs - the serratus anterior - becomes twisted in the process but keeps its ancestral attachment to both bones (see above). Other muscles, particularly those that power the limbs, form very different connections.

In mice and chicken, the large latissimus dorsi muscle (which connects the top of the forearm to the back) initially grows out from the embryo's limb bud, attaches to its trunk, and starts expanding backwards to cover the back. In the turtle embryo, the growing muscle attaches to the front part of the developing shell, near the neck. Likewise, the pectoral or chest muscles of chickens and mice grow from the limbs into the sternum, but those of turtles connect to the plastron - the bottom half of the shell. These new connections account for the bizarre differences between the musculature of adult turtles and other vertebrates.

Nagashima also suggests that his findings secure the place of a recently discovered fossil turtle - Odontochelys - as an intermediate form between shell-less turtles and modern versions. Odontochelys was a turtle in a half-shell, whose armour had a lower half (a plastron) but not a top one (a carapace). Its discoverers suggested that it was a sign that turtles evolved via a half-shelled form, but other scientists claimed that it could equally be a descendant of fully-shelled turtles that had itself lost half its shell.

Odontochelys also had short ribs on its back that seem to have stopped growing early. Its second set of ribs, however, never grew to cover its shoulder blade, which still sat in front of the entire rib cage. That matches the body plan of modern turtle embryos in the early stages of development, which supports the idea that this extinct turtle represented an ancestral pattern.

The short ribs of Odontochelys suggests that like modern turtles, it had a carapacial ridge and was on the way to completing the top half of its armour. Nagashima suggests that the ridge only extended down its flanks but didn't meet at the front and back (note the dotted red line in the image below). It may have been this simple step that provided the impetus for the movement of the second pair of ribs to cover the shoulder blade, the evolution of the carapace, and the completion of the turtle's armour.

Reference: Science 10.1126/science.1173826

Images: from Singeru Kuratani, Hiroshi Nagashima and Science/AAAS

More on turtles: Heroes in a half-shell show how turtles evolved

edyong Thu, 07/09/2009 - 10:00

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Very cool - thanks. It would be interesting to look at how the R1 & R2 ribs become shortened. It appears in the literature as if the development of the distal part of the rib is controlled by a different mechanism to the proximal part which provides a relatively simple pathway for evolution to exploit. I wonder if they use the same mechanisms that other vertebrates use to shorten the lumbar ribs? The muscles are just wierd though...

That is very cool. One of my children does origami, so the analogy helped me visualize it.

THE AWESOME, IT BURNS. Seriously, the teaser for this paper was at SVP last year and I couldn't wait until it was published. The scapula is inside the shell, but OUTSIDE the ribcage. Too cool!

But the teenage mutant ninja turtles seem to have regular shoulder blades! Explain that will ya :-)

It is really?so improbable.

Is there an analogous development in tortoises?

Exactly the same. The different names are more than a little confusing, but for an evolutionary biologist, they bear little significance. See here: http://en.wikipedia.org/wiki/Turtle#Turtle.2C_tortoise.2C_or_terrapin.3F

Wh...what? A tortoise is a kind of turtle.

I'd have said a turtle was a kind of tortoise :-)