A Blueprint for Self‐Sharpening: Optimized Geometric Design Coupled With Multiscale Architecture in Northern Snakehead Teeth

ABSTRACT The northern snakehead (Channa argus), an apex freshwater predator, possesses teeth that are a masterclass in biological design, achieving exceptional puncture resistance and autonomous self‐sharpening with minimalist material use. Here, through a multiscale investigation combining structural characterization, chemical mapping, and mechanical analysis, we decipher the key architectural principles underlying this evolutionary innovation. We reveal a thin enameloid cap with a functionally graded structure: a highly aligned, fluorapatite‐rich outer layer provides superior hardness (5.0 GPa), while a disordered inner layer enhances toughness through crack deflection. This efficient “hard‐soft” laminate is synergistically supported by a unique “mountain‐peak”‐shaped dentin‐enameloid junction (DEJ) that dissipates stress, and a dentin core reinforced with aligned collagen fibers and a hierarchical canal network for energy absorption. Crucially, we demonstrate that the tooth's physiological curvature is not merely morphological but functional, guiding asymmetric wear on the concave side to continuously regenerate a sharp apex—a mechanism directly visualized via in situ compression 3D tomography. This work establishes the northern snakehead tooth as a model for efficient puncture, offering fundamental design blueprints for the next generation of biomimetic materials, particularly for lightweight, self‐sharpening, and puncture‐resistant devices.