Unique structures and material properties of the skin in different body regions of three species of fish

Abstract

Benefitting from its unique helically arranged fiber structures, fish skin is a superior biological protective tissue. Reported here is a study of the microscopic morphological characteristics and mechanical properties of the skin of three species of fish, that is, Taihu white fish (Erythroculter ilishaeformis), grouper (Cichlasoma managuense), and yellowfin seabream (Ditrema temminckii Bleeker), revealing the special protective mechanisms of fish skin. Experiments involving scanning electron microscopy show that the stratum compactum is the main part of fish skin and comprises helically stacked fibers, with the helical ply angles of the fibrous layers differing significantly for the different fish species and in different regions of their bodies. Tension and penetration experiments show that fish skin provides a fish's body with considerable mechanical protection from lacerations and bites inflicted by its natural enemies. Moreover, the mechanical tests show that fish skin has two different defensive mechanisms against tension and penetration loads, thereby offering a novel idea for designing body armor that is both flexible and tough.

The Flexible Armor of Chinese Sturgeon: Potential Contribution of Fish Skin on Fracture Toughness and Flexural Response

“…The authors further revealed that s. compactum plays an essential role in fish movement and protective functions and significantly improves the biomechanical properties of fish skin. Furthermore, Zheng et al studied the mechanical protective behaviors of the fish skin of three different fish species living in different water areas, namely Taihu white fish ( Erythroculter ilishaeformis , from freshwater), grouper ( Cichlasoma managuense , which live in both freshwater and seawater), and yellowfin seabream ( Ditrema temminckii Bleeker , from the ocean) [ 13 ]. They found that for the three fish species, s. compactum plays a vital role in the protective behaviors of the fish skin.…”