Sharks don’t have bones. Instead, their skeletons are made from mineralized cartilage that helps them constantly move through water. To understand the internal “sharkitecture” that helps keep these animals strong and graceful, researchers are putting sharks under the microscope. A new study, published in ACS Nano, found some surprising results. After analyzing shark cartilage, there appear to be two different regions within it. And each appears to have vastly different structures. These structures have shown a resistance to destruction and could inspire strong, flexible materials for the future. Analyzing a Shark Skeleton An X-ray nanotomography reconstruction of the intermedial cartilage of a blacktip shark. The colors indicate the thickness of the struts, with red representing thicker areas and blue indicating thinner ones. (Image Credit: Florida Atlantic University)Sharks are powerful and efficient creatures. Thanks to their skeletal frame, made of mineralized cartilage, their spines can act like a spring, which stores and releases energy as they move their tails, according to a press release. Wanting to better understand how this cartilage helps keep sharks atop the ocean’s food chain, researchers from the Charles E. Schmidt College of Science and the College of Engineering and Computer Science at Florida Atlantic University (FAU), in collaboration with the German Electron Synchrotron (DESY) in Germany, and NOAA Fisheries, have analyzed blacktip sharks (Carcharhinus limbatus) and mapped out their internal structure. The team used synchrotron X-ray nanotomography with detailed 3D imaging and in-situ mechanical testing to create the map. The results showed that on a nano level, the blacktip shark’s cartilage had two distinct regions, the corpus calcareum and the intermediale. Though both of these regions are made up of densely packed collagen and bioapatite, they have vastly different internal structures. Strong Microscopic Structures According to the study, in each region, the cartilage is porous and also has thick struts that help the skeleton with strain from multiple directions. This is a key adaptation as sharks are continuously moving and putting pressure on their spines.  Researchers also found microscopic needle-like bioapatite crystals, similar to those in human bones, that were lined up with strands of collagen. This is another factor that gives shark cartilage extra strength and flexibility. Along with that, the research team also noted helical fiber structures, also with collagen, which suggests the cartilage is designed to prevent any cracks from spreading, and help to distribute staring and force. “Nature builds remarkably strong materials by combining minerals with biological polymers, such as collagen – a process known as biomineralization. This strategy allows creatures like shrimp, crustaceans, and even humans to develop tough, resilient skeletons,” said Vivian Merk, senior study author and an assistant professor in the FAU Department of Chemistry and Biochemistry, in a press release.“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,” Merk added in the release. Shark Inspiration for MaterialsThe research team applied pressure to microscopic pieces of the shark’s vertebrae and found deformations, smaller than one micrometer. The team only noticed fractures in the vertebrae after a second round of pressure was applied. But even then, the fractures were only found within one mineralized plane, proving how strong the material was. “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 Marianne Porter, study co-author and an associate professor in the FAU Department of Biological Sciences, in a press release. “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,” Porter added in the release.Article SourcesOur writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:A graduate of UW-Whitewater, Monica Cull wrote for several organizations, including one that focused on bees and the natural world, before coming to Discover Magazine. Her current work also appears on her travel blog and Common State Magazine. Her love of science came from watching PBS shows as a kid with her mom and spending too much time binging Doctor Who.