Mechanical properties of pufferfish (Lagocephalus gloveri) skin and its collagen arrangement

Skin is a biological material the mechanical properties of which are dependent on the constituents from which it is assembled. Skin, the outer covering of animals is made up of collagen fibers arranged in more or less ordered arrays. Pufferfish skin provides a rigid framework to support the body contents and a flexible covering to allow whatever changes are necessary for the remarkable inflation mechanism. Here, we describe the structure and tensile properties of the dorsal and ventral skin of the pufferfish, Lagocephalus gloveri Abe and Tabeta, 1983. The ultimate tensile strength of ventral skin was found to be around two times higher than that of the dorsal skin. It was observed that the dorsal skin could resist more deformation than the ventral skin. The collagen fibers were arranged in different ordered arrays for ventral and dorsal skin and the concentration of fibers was found to be more in ventral than dorsal skin. This provides more stiffness to ventral skin. Scanning electron microscopy studies of the ventral skin showed a unidirectional arrangement of the collagen fibers, which provides more stretching capacity. Dorsal skin, on the other hand, has an orthogonal arrangement of fibers. The present study thus showed that the mechanical behavior of the skin of L. gloveri is strongly influenced by the concentration and arrangement of collagen fibers.