Comparative biomechanics of hagfish skins: diversity in material, morphology, and movement

The baggy skins of hagfishes confer whole-body flexibility that enables these animals to tie themselves into knots without injury. skin’s looseness is produced by a subcutaneous blood sinus decouples the skin and body core permits contort dramatically loading in tension or shear. Hagfish represents biological composite material comparable strength stiffness conventionally taut other fishes. However, our understanding hagfish restricted only one 78 species: Pacific Eptatretus stoutii. To determine if share similar characteristics with E. stoutii, we measured properties compared histological data sets from four springeri, Myxine glutinosa, M. hubbsi. We also American eel, Anguilla rostrata. subjected samples all species uniaxial tensile tests order measure strength, stiffness, extensibility, toughness stretched along longitudinal circumferential axes. used series equibiaxial on A. rostrata simultaneously strained both Significant results biaxial show are anisotropic, being stiffer axis, more extensible than isotropic Myxine. Skins were axis they stronger, tougher, examined. histologically distinct possess arrays fibers stain like muscle. These interspecific differences across phylogenetic pattern knotting kinematics flexibility; genera belong but major subfamilies within Myxinidae, known for creating manipulating greater diversity styles