Shark skeletons could lead to technological innovations

Sharks have glided through oceans for more than 450 million years, relying on skeletons made not of bone but of stiff, mineralised cartilage.

Their vertebral columns act like coiled springs, storing and releasing energy with every tail beat, even as the fish reach speeds of twenty miles per hour or vault clear of the water in spinning leaps.

Scientists have long known that this mechanical efficiency stems from a cleverly reinforced spine, yet only now are researchers imaging those reinforcements at the nanoscale.

Mapping cartilage in 3D

A team from Florida Atlantic University (FAU), the German Electron Synchrotron (DESY), and NOAA Fisheries used synchrotron X-ray nanotomography to map the internal architecture of blacktip shark vertebrae in three dimensions.

They paired scans with mechanical tests, squeezing tiny segments while tracking how they bent and cracked. The images revealed two layers inside the mineralized cartilage: a hard outer shell (corpus calcareum) and a softer inner core (intermediale).

Both zones are packed with collagen fibers infused with bioapatite, the same calcium-phosphate mineral that stiffens human bone. Yet their arrangements differ.

Porous plates of mineralized tissue are supported by thick struts, allowing the shark skeleton to resist forces from many directions. This is essential for an animal that swims continuously and bends its body thousands of times each hour.

At even higher magnification, the scientists saw needles of bioapatite aligned with the collagen strands. They also discovered helically wound fiber layers that resemble plywood on a microscopic scale.

Under load, those helices hinder cracks from running unchecked, distributing stress through a web of stiff mineral and stretchy protein.

Nature’s recipe for resilience

Study senior author Vivian Merk is an assistant professor of chemistry, ocean and mechanical engineering, and biomedical engineering at FAU.

“Nature builds remarkably strong materials by combining minerals with biological polymers, such as collagen – a process known as biomineralization,” said Merk. “This strategy allows creatures like shrimp, crustaceans, and even humans to develop tough, resilient skeletons.”

“Sharks are a striking example. Their mineral-reinforced spines work like springs, flexing and storing energy as they swim. By learning how they build such tough yet adaptable skeletons, we hope to inspire the design of next-generation materials.”

Under compression, vertebrae yielded slightly on the first cycle and cracked only after a second round of stress. Even then, the fracture plane remained confined to one mineral layer, evidence that the helices and porous scaffolds localize damage rather than letting it propagate.

“After hundreds of millions of years of evolution, we can now finally see how shark cartilage works at the nanoscale – and learn from them,” said co-author Marianne Porter, an associate professor of biological sciences at FAU.

“We’re discovering how tiny mineral structures and collagen fibers come together to create a material that’s both strong and flexible, perfectly adapted for a shark’s powerful swimming. These insights could help us design better materials by following nature’s blueprint.”

Shark skeletons inspire design

Blacktip sharks roam warm coastal waters worldwide. Their quick turns and aerial spins place punishing loads on the spine, making them ideal models for impact-resistant design.

The layered “sharkitecture” identified in the study could guide the development of everything from lighter body armor to longer-lasting joint implants.

“This research highlights the power of interdisciplinary collaboration,” said Stella Batalama, dean of FAU’s College of Engineering and Computer Science. “By bringing together engineers, biologists, and materials scientists, we’ve uncovered how nature builds strong yet flexible materials.”

“The layered, fiber-reinforced structure of shark cartilage offers a compelling model for high-performance, resilient design, which holds promise for developing advanced materials from medical implants to impact-resistant gear.”

Cartilage wins in evolution

Unlike bony fish, sharks never switch to a calcium-phosphate skeleton during development. Their cartilaginous framework, reinforced by bioapatite only at strategic sites, saves weight without sacrificing stiffness.

The new nanoscale images suggest evolution achieved that balance through multiscale ordering. Collagen fibrils form bundles, which twist into helices. These helices embed in mineral plates, which then stack into porous columns that combine load-bearing strength with flexibility.

Because collagen and bioapatite are common to many vertebrates, the principles observed in sharks could be translated to human health.

Engineers might mimic the helical layering to make fracture-resistant composites, or apply the plate-and-strut motif to maximize strength while retaining lightness in aerospace parts.

Surgeons could one day use customized implants modeled on shark cartilage to promote bone integration and reduce fatigue failure.

Shark tech from the deep

The study adds to a growing inventory of marine organisms whose microstructures inspire technology, from manta-ray-inspired filters to cephalopod-inspired camouflage. Shark spines now join that list, revealing how evolution transforms humble ingredients – protein and mineral – into a mechanical masterpiece.

Further research will probe other species, life stages, and environmental stresses. Mixed-phase cartilage from hammerheads or deep-sea lantern sharks may reveal different configurations tuned to unique swimming styles or pressure regimes.

Each discovery will refine the emerging field of deep-sea biomimetics, where ancient adaptations inform tomorrow’s materials.

For engineers seeking to reconcile strength, flexibility, and damage tolerance, few tutors rival the blacktip shark. It has been perfected by 450 million years of relentless motion through saltwater and time.

The study is published in the journal ACS Nano.

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