Printed Shark Skin

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Printed shark skin reported in ScienceShots and BBC News 14 May 2014 and Journal of Experimental Biology 15 May 2014 doi: 10.1242/jeb.107342. Sharks appear to have smooth skin, but it is actually as rough as sandpaper, because the skin surface is covered with tiny overlapping bony scales, called denticles. These are shaped like grooved teeth, and it has been assumed that they decrease the drag of flowing water as it passes over the skin surface when the shark is swimming, enabling it to move faster and save energy. However, it has not been possible to test the effect of the denticles because that would involve testing a skin surface with and without the denticles and, as George Lauder of Harvard University explained, “You can't modify real shark skin”. Lauder and colleagues set out to produce an artificial shark skin.

They first scanned the skin of a shortfin Mako shark and made a detailed computer model of the denticles, but then they had to find a way of reproducing them in the same overlapping way as on the real shark skin, attached to a flexible surface. After a year of experimenting with different materials and 3D printing protocols, they were able to produce hard denticles on a flexible membrane, which they could then use for hydrodynamic testing.

After comparing the membrane with and without the denticles they discovered the denticles reduced the drag of water flowing over a stationary membrane by 8.7%. They then tested the membrane by moving it in a swimming motion and found the denticles increased swimming speed by 6.6% and reduced energy expended by 5.9%. That may not seem like much difference but, according to Lauder, “That’s a huge effect, when factored over the entire lifetime of an animal that is constantly swimming”. Sharks do not have a swim bladder and need to keep moving all the time or they sink. Lauder told BBC News “It pays us to understand how the natural world works. Millions of years of evolution give us solutions to problems that we may not have thought of”.

ScienceShot, BBC

Editorial Comment: It is certainly good to understand how the natural world works, but the more scientists and engineers try to copy the natural world the more they establish that chance random evolution did not produce it. Time and chance could no more produce real shark skin than it did the artificial shark skin, which only came about because intelligent scientists studied the structure of real shark skin, used their knowledge of chemical substances to find some that could be shaped into denticles, and then programmed the 3D printer to produce it.

We remind them that the real denticles on real shark skin are also there because the living equivalent of the 3D printer, i.e. skin cells, have been programmed with information via the genetic code carried on DNA. The information for the artificial skin only got into the 3D printer because intelligent pre-existent scientists put it there. However, the same scientists are not using their intelligence when they believe DNA information got into cells without any creative design. (Ref. design, biomimetics, fish, biomechanics)

Evidence News, vol. 14, No. 8
21 May 2014
Creation Research Australia