February 9, 2016 | David F. Coppedge

Small Creatures Have Super Strength

The most amazing physical feats in nature are performed by some of the smallest organisms.

Super-cockroach: Scientists put some cockroaches through a squeeze test and were astonished. Look what they say in PNAS:

Amazing FactsCockroaches intrude everywhere by exploiting their soft-bodied, shape-changing ability. We discovered that cockroaches traversed horizontal crevices smaller than a quarter of their height in less than a second by compressing their bodies’ compliant exoskeletons in half. Once inside vertically confined spaces, cockroaches still locomoted rapidly at 20 body lengths per second using an unexplored mode of locomotion—body-friction legged crawling. Using materials tests, we found that the compressive forces cockroaches experience when traversing the smallest crevices were 300 times body weight. Cockroaches withstood forces nearly 900 times body weight without injury, explaining their robustness to compression.

Now you understand why they are so hard to fight in the kitchen. The scientists, though, got excited about what they learned: Cockroach exoskeletons provided inspiration for a soft, legged search-and-rescue robot that may penetrate rubble generated by tornados, earthquakes, or explosions.” Science Daily shares more about cockroaches and the bio-inspiration they provide. Live Science shows a video of the compressive material (warning: annoying music).

Super diatom: How can a little microbe win the gold for strength? It’s incredible. In another paper in PNAS, a team found the following:

Diatoms are unicellular algae that form an intricate silica cell wall. A protective shell that is light enough to prevent sinking while simultaneously offering strength against predators is of interest to the design of lightweight structural materials. Using three-point bending experiments, we show that the diatom shell has the highest specific strength of all previously reported biological materials. Fracture analysis and finite element simulations also suggest functional differentiation between the shell layers and features to mitigate fracture. These results demonstrate the natural development of architecture in live organisms to simultaneously achieve light weight, strength, and structural integrity and may provide insight into evolutionary design.

While “evolutionary design” is a sophoxymoronic phrase, it’s incredible to think about the physics of this little glass structure in which a soft little alga lives. Ounce for ounce, the diatom wins over bones, teeth and antlers, PhysOrg says. The secret is a honeycomb-like pattern of holes that provides strength while allowing nutrients in and waste out.

“Silica is a strong but brittle material. For example, when you drop a piece of glass, it shatters,” says Greer. “But architecting this material into the complex design of these diatom shells actually creates a structure that is resilient against damage. The presence of the holes delocalizes the concentrations of stress on the structure.”

Again, these scientists see possibilities from what they learned about diatom design. “The group plans to use design principles from diatoms to create resilient, bioinspired artificial structures,” PhysOrg says.

Update 2/11/16: Boxing Ants: Science Daily tells how American biologists watched ants strike each other’s antennae to determine rank in the colony. “Trap-jaw ants are the fastest boxers ever recorded,” they commented. Muhammed Ali had nothing on these champs. “The speeds ranged from 19.5 strikes per second for Odontomachus rixosus, hailing from Cambodia, to a blazing-fast 41.5 strikes per second for Odontomachus brunneus, native to Florida, the researchers found.” Winners get to go out and forage; the weaklings had to stay inside the nest.

Why would evolution confer such design on a tiny diatom? When would it ever encounter forces needing that kind of super-strength? And why would evolution design each diatom shell as a geometric shape on which is carved intricate patterns?

In his new book Evolution: Still a Theory in Crisis, Dr. Michael Denton brings his influential 1985 classic up to date after 30 years of thinking about Darwinism. He focuses heavily on “non-adaptive design” that could never come about by natural selection. Surely these examples qualify for that designation.



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