Diabolical ironclad beetles inspire extra-strong joints
One type of beetle is so tough that you could run it over and it would still walk away. This is the ‘diabolical ironclad beetle’ (Nosoderma diabolicum, formerly Phloeodes diabolicus), found in the southwestern USA.
This beetle is only 2 cm long, or under an inch, but can survive a force of 149 newtons. This is equivalent to the weight of 15 kg, or about 39,000 times the beetle’s own weight. It is also 2.5 times as much as the average male university student can exert between thumb and index finger,1 and about 10 times the bite strength of potential predators. The ironclad beetle is sometimes known as ‘pin-bender’, because pins will bend rather than penetrate, unless a hole is drilled first.2
What makes the ironclad beetle so tough?
This beetle’s toughness was intriguing, especially with no mineral in its exoskeleton, unlike shells or bones.3 A team led by David Kisailus, a materials scientist and biomimeticist at University of California, Irvine, worked out the intricate fine structure that greatly increased toughness.4
The wing-cases (elytra, see box) are joined to the underside of the exoskeleton. Over the beetle’s vital organs, the join is interdigitated, i.e. similar to interlocking fingers. Like columns of a bridge, the ‘fingers’ resist compression. But resistance can only go so far. Sometimes material must yield or break. This is why tall buildings in earthquake-prone areas are often supported on flexible bearings that allow some swaying.5 So too with the beetle: in places further from the vital organs, the joints are latched or free-standing, which allows the exoskeleton to yield under pressure.
The other feature is the suture joining the two elytra. The suture comprises interlocking halves called blades, and they are shaped like jigsaw puzzle pieces. The blades have an elliptical shape, which turns out to be stronger than triangular or semicircular blades found in other beetles.3 Dr Kisailus said, “If you take two pieces of that jigsaw puzzle, and you try to pull them apart, once they’re attached, it’s a pretty robust interface. And so that is what provides the beetle with strength.”2
Another strength enhancer is the layered (laminated) structure. Kisailus explained (emphasis in original), “That’s what defines the toughness in this organism—it provides a lot of energy dissipation instead of failing brittlely. It just de-laminates.”2
Application to aircraft design
Often, joints are the weakest part of any structure. They can fail catastrophically, which can be deadly, e.g. in airplanes. The newest airplanes are often made largely of composite materials that combine lightness and strength. However, it’s hard to make strong joints between different types of material, such as carbon-fibre composites to metals. Rivets and glues can fail, as can traditional fasteners.
Kisailus and his team joined carbon-fibre-reinforced composite to aluminium plates with a traditional fastening pin used in aerospace engineering. Then they made plates with a laminated structure and edges milled to mimic the ironclad beetle’s suture.
Under stress, the traditional fastener failed catastrophically. However, with the beetle mimic, the delamination took much of the energy, and the separation of layers made the structure expand and grip more tightly. Any fracturing is both more gradual and more predictable, which could lead to easier inspection to detect cracking earlier.3
Evolution or design
Although evolution provided no practical help here, a homage to evolution is compulsory in many quarters. One beetle expert said, “the trait probably evolved as a defense against predators.”2 But evidence was neither asked for nor given. The non-sequitur “advantage, therefore evolution” crops up in a lot of places.6 What is missing is the series of small, gradual steps, each having an advantage over its predecessor.
Rather, it makes more sense to use an argument from analogy, as Darwin often did. That is, it took intelligent engineering to make the copies, so how much more so to make the originals?
Beetles belong to the insect order Coleoptera (Greek koleos = sheath, pteron = wing). Aristotle (384–322 BC) coined this name because both forewings are thickened to form protective sheaths called elytra (singular elytron). Flying beetles lift up their elytra to free the hindwings to fly. Non-flying beetles often have their elytra fused.
Coleoptera is the largest order of any animal—400,000 species, about 25% of all animal species.7 Biblical creationists in general point out that the created kind usually comprises different ‘species’ and even different ‘genera’.8
About 20% of beetles are weevils (Family Curculionidae). Beetles live everywhere on the earth apart from the sea and on ice. They include the largest living insect, the Goliath beetle—mass 115 g (4.1 oz) and length 11.5 cm (4.5 in). Some beetles are pests, because they eat crops, but others, such as ladybirds, eat pests.
Beetles, like other insects, have exoskeletons made of protein plus chitin, a polysaccharide. This combination forms fibres that form a laminated structure. This structure means that cracks can’t propagate through the layers, making the exoskeleton hard to break. But this alone is insufficient to explain the extra toughness of the ironclad beetle.9
The atheistic evolutionist J.B.S. Haldane often said that if a creator exists, then he “has an inordinate fondness for stars and beetles” because he made so many of them.10 Entomologist Dr Gordon Wilson replied:
“When God makes the kinds, there are many roles for them, only one of which is ecological. It’s easy for biologists to miss other things, like the creativity and lavishness of God. And the aesthetic value—they exist for His pleasure as well as ours. Many beetles are incredibly beautiful.”11
References and notes
- Bretz, K. and Jobbágy, Á, Force measurement of hand and fingers, Biomechanica Hungarica 7 Jan 2010. Return to text.
- Simon, M., How the ‘diabolical’ beetle survives being run over by a car, wired.com, 21 Oct 2020. Return to text.
- Chen, P.-Y., Diabolical ironclad beetles inspire tougher joints for engineering applications, Nature 586:502–504, 21 Oct 2020. Return to text.
- Rivera, J. and 9 others, Toughening mechanisms of the elytra of the diabolical ironclad beetle, Nature 586:543–548, 21 Oct 2020. Return to text.
- Halting the jolts: How Te Papa resists earthquakes, tepapa.govt.nz. Return to text.
- Doyle, S., Does biological advantage imply biological origin? J. Creation 26(1):10–12, 2012. Return to text.
- Stork, N.E. and 3 others, New approaches narrow global species estimates for beetles, insects, and terrestrial arthropods, PNAS 112(24):7519–7523, 16 Jun 2015. Return to text.
- Sarfati, J., Startling sturddlefish, Creation 43(1):17, 2021. Return to text.
- Chen, ref. 2. Return to text.
- “The creator has an inordinate fondness for beetles”, quoteinvestigator.com, 23 Jun 2010. Return to text.
- Bugs, baramins and beauty, Carl Wieland chats with insect expert Gordon Wilson, Creation 30(3):42–44, 2008. Return to text.