Sea urchins hold building material clues

2012-02-14 08:15

Cape Town - Scientists have discovered that the chalk produced by sea urchins may hold clues to stronger buildings materials.

A team led by Dr Helmut Cölfen from the University of Konstanz in Germany discovered how the marine animals used lime to grow spines that are hard and flexible.

The animals have calcite crystals that are embedded, like bricks in a wall, into a mortar of amorphous lime mixed with small amounts of biological proteins.

When sea urchin spines are broken, they produce a rough surface, yet they are tough because they consist of lime (calcium carbonate). In geological deposits, lime usually forms calcite crystals that have very different properties to sea urchin spines as they break easily along their cleavage planes.

The team used an X-ray technique to reveal that sea urchin spines are actually built like walls of nanometre-sized bricks of calcite crystals which are aligned in parallel. The bricks are glued together with a mortar of non-crystalline lime.


The arrangement creates an elastic type of material that absorbs shocks.

"It was a real challenge to separately characterise the crystalline and non-crystalline parts of the spines, because the individual structures are extremely small. We had to combine two very different techniques using thin X-ray beams, one optimised for nanocrystals and the other for amorphous structures," said Aurélien Gourrier of the European Synchrotron Radiation Facility (ESRF) in Grenoble.

The researchers determined that 92% of the spines consist of crystalline calcite and 8% of amorphous lime. The disordered lime is in turn made of 99.9% calcium carbonate into which a tiny 0.1% of proteins are mixed. At a disordered layer thickness of one or two nanometre around the calcite crystals, it ensures that the sting can only be broken with difficulty.

"It is fascinating that nature can turn fragile materials through structuring into high-performance composite materials, that manufacturing has not managed to produce so far," said Cölfen.

His group is collaborating with a two companies to dedicated to producing high-performance concrete, using the discovered technology.

The research was published in the Proceedings of the National Academy of Sciences.

  • Ally - 2012-02-14 09:12

    Another little wonder of the world.

  • Jan - 2012-02-14 09:51

    God's creation is truly wonderful. Just when we think we know it all, we discover how little we really know.

      Artur - 2012-02-14 10:04

      Evolution is truly amazing

  • thilo.klingenberg - 2012-03-19 09:40

    Since I saw a sea urchin for the first time in a fish tank at our favourite sushi restaurant, looking at it builds my faith in God and His creation. When you look at this creature which is an animal but looks like a plant and see purple and diamond like spots on the exterior which are perfectly symmetrical! The information in this article just confirms for me how wonderful God is. I am sorry Artur but you have more faith than I have. I have enough faith to believe in a Creator God but not enough to believe in Evolution. I would need much more faith to believe that the symmetry of the decorative spots on the outside and the use of two different types of lime in perfect ratios and consistency, etc etc purely happened by chance. All evolutionists should play the Lotto. You have a way better chance of winning the Jackpot than the sea urchin getting the ratio of crystalline calcite and amorphous lime right by chance.

  • thilo.klingenberg - 2012-03-19 09:44

    Just another thought which I would like the Evolutionists out there to answer: why hasn't life, plants, animals etc that can breathe on Nitrogen (as it is the most common gas in the atmosphere) developed at least to the same extent as the current life forms on earth which need Oxygen to survive? After all if it all happenend by chance over time, surely the chance of complex life forms not needing Oxygen should be much more prevalent, also on the other planets just in our Solar system?

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