Friday, May 21, 2010

A Deep-Sea Snail and Evolution’s Superior Material Designs

Once again evolution has come up with an ingenious design, this time a multilayered protective material with a range of potential applications. The material was discovered in the shell of a deep-sea snail, Crysomallon squamiferum, which is able to withstand powerful crab attacks. Here is the summary of the new findings:

Biological exoskeletons, in particular those with unusually robust and multifunctional properties, hold enormous potential for the development of improved load-bearing and protective engineering materials. Here, we report new materials and mechanical design principles of the iron-plated multilayered structure of the natural armor of Crysomallon squamiferum, a recently discovered gastropod mollusc from the Kairei Indian hydrothermal vent field, which is unlike any other known natural or synthetic engineered armor. We have determined through nanoscale experiments and computational simulations of a predatory attack that the specific combination of different materials, microstructures, interfacial geometries, gradation, and layering are advantageous for penetration resistance, energy dissipation, mitigation of fracture and crack arrest, reduction of back deflections, and resistance to bending and tensile loads. The structure-property-performance relationships described are expected to be of technological interest for a variety of civilian and defense applications.

C. squamiferum’s shell is truly an evolutionary breakthrough providing material science with several new concepts for protective armoring. As one report explains:

the snail employs some unique tricks to protect itself. For example, the shell's outermost layer consists of strong particles of iron sulphide created in the hydrothermal vents, each around 20 nanometres across, embedded in a soft organic matrix secreted by the snail. This structure is designed to crack when hit, but in a way that absorbs energy.

Cracks spread only by fanning out around the iron sulphide particles. This "microcracking" not only absorbs energy, it also ensures that larger cracks do not form. What's more, the particles of iron sulphide may blunt and deform intruding claws …

A thick, spongy middle layer acts as padding to dissipate further the energy of the blow. This makes it less likely that the mollusc's brittle inner shell, which is made of calcium carbonate, will crack. …

Helmets, motorbikes and Arctic pipelines that collide with icebergs, leading to costly oil spills, could also benefit ...

C. squamiferum’s revolutionary shell design is yet another reason why evolution is so important to science as a whole.


  1. What evolutionary prediction was falsified by this finding?

    What metaphysical or religious preconceptions were shattered by this finding?

    How did evolutionary thinking hinder this discovery?

    Is it an embarrassment? Will it be swept under the rug?

  2. I wonder . . .

    I wonder what story evolutions will invent to explain how C. squamiferum survived for millions of years waiting for its armour to evolve.

    I wonder what engineering firm C. squamiferum contracted out to have such a sophisticated protection developed for itself. The army should hire the materials engineer responsible for the project.

    I wonder why, if evolution is true, crabs didn't starve to death and become extinct because all the creatures they prey on would tend to develop these types of protection mechanisms.

  3. "I wonder what story evolutions will invent to explain how C. squamiferum survived for millions of years waiting for its armour to evolve."

    With this argument, you just proved that slugs don't exist. Congratulations.

  4. there seem to be 2 "arguments" here
    1) "look how complex this structure is, how could evolution have done that?"

    2)"evolutionary biology wasn't used to make this discovery, therefore evolutionary biology is not as useful as Dobzhansky says it is"
    1) is standard creationism/ID fare.
    2) is pretty bizarre. has anyone ever claimed that all biological research must be evolutionarily based? this is like pointing to a paper on butterfly ecology and saying "look how useless proteomics is!"

  5. Re nanobots second point, the website of Dr. Ortiz suggests her work is evolution-inspired, and follows on the macroscopic observations of century of evolutionary biology.

    "Such systems have developed hierarchical and heterogeneous composite structures over millions of years of evolution in order to sustain the mechanical loads experienced in their specific environment. For this reason, they have enjoyed a long and distinguished history in the literature of more than a century with an emphasis on macroscopic, continuum-level biomechanics. The Ortiz research group studies these fascinating materials using expertise in the field of “nanomechanics” including; the measurement and prediction of extremely small forces and displacements, the quantification of nanoscale spatially-varying mechanical properties, the identification of local constitutive laws, the formulation of molecular-level structure-property relationships, and the investigation of new mechanical phenomena existing at small length scales."

  6. Robert,
    I still think it would be a stretch to say that this research is based in any significant way on evolutionary biology.. for that same reason I would also say the research is pretty boring, but that's just me :)

  7. nano-

    I think I over-read that paragraph a bit.
    Sure, material science is not evolutionary biology, and I'm not going to be citing her papers as evidence of common descent (yet?).

    But, quick checks show evolutionary logic is found in her work. She compares bio-materials from one species to the closest relative.

    Personally, I'd be really interested in the molecular evolution of these pathways, perhaps in hopes of recapitulating them in a model organism. But that's me.

    I guess my point is, that even in this apple to evolutionary biology's orange, there is evolutionary thinking, there is benefit in evolutionary thinking, and clear ways a 'hardcore' evolutionary biologist might run with this to the benefit of many.

  8. One theme of this blog is “it too complex thus it can't have evolved”. These kind of entries are labeled with “Complexity” like this one is. Needles to say that in the scientific community this argument does not sell well.

    What surprises me is how unscientific this argument is. Imagine this: If one could measure the complexity quantitatively then one would assume that the argument would be: The system's complexity is above a threshold x thus it can't have evolved. Then to argue about individual systems would be pointless since it would already be clear that one side thinks that that system can't have evolved. Since the complexity can't be measured the only way seems to be to repeat this argument for each individual system.

    Depending on the current amount of knowledge it is then hence more or less plausible that that system could have evolved. But this whole procedure is not only rather pointless but also unsystematic and thus unscientific. In science we can't drop a stone an infinite number of times to be sure that it will fall every single time. In order to make progress we need to induce that it will fall after a finite number of tries and move on. Thus we can't argue about every single complex system but have to, at some point, decide whether these systems can have evolved or not.

  9. Evolutionis site poor desing as proof that there is no designer. But then really superb design should be proof of a designer.

  10. @natschuster

    That poor design is proof of no designer is not a scientific argument. This argument, with exceptions, is only used in public debates. The scientific question is: Why is there bad design and good design at the same time?

  11. It's amazing that the Blind Watchmaker has so much more creative power than all the world's scientists and engineers, combined.

    The Blind Watchmaker truly is praiseworthy.

  12. How do you define bad design? Maybe good enough design is good.

  13. How do you define superb design? Maybe superb design is just good enough.

    I don't want to play just ping pong here. Unless you measure the quality of design quantitatively the argument is useless but that goes both ways.

  14. I would imagine that a design that is so good that engineers are studying it to get ideas for new applications could be defined as superb. And a design that works could be called good enough.

  15. Another day, another ID 'argument' consisting of nothing but loud proclamations of ignorance-based personal incredulity.


  16. Well, you guys show us a random mutation through natural selection that makes this amazing leap of complexity to clear things up, plz.