Meeting Abstract

P1.203  Friday, Jan. 4  Material Properties of Taut and Slack Skins in Elongate Fishes CRAWFORD, C.H.*; KING, B.D.; CLARK, A.J.; College of Charleston; College of Charleston; College of Charleston crawford.callie@gmail.com

The mechanical response of fish skin to tensile stresses produced by axial bending during swimming could vary with tautness. High skin tautness in lamprey, cartilaginous fishes, and bony fishes results from myoseptal tendinous connections between the skin and axial muscles. Hagfishes possess loose-fitting skin due to the absence of these myoseptal connections yet employ the anguilliform mode of swimming also used by elongate taxa with tighter skin. We compared the tensile mechanics of loose skin from Pacific hagfish, Eptatretus stoutii, with tight skin from sea lamprey, Petromyzon marinus, and penpoint gunnel, Apodichthys flavidus. Skin samples were dissected from dorsolateral surfaces at 25% and 75% TL, and then subjected to quasi-static uniaxial tensile tests to failure. We measured strength (peak stress) and stiffness (Young’s modulus) from E. stoutii skin and A. flavidus skin loaded in both longitudinal and circumferential directions, and stiffness from P. marinus skin loaded longitudinally. Mean stiffness and strength in all species examined occur within the range observed in other fishes. Neither strength nor stiffness differed significantly with respect to location on the body in any species. Hagfish and gunnel skins are anisotropic, with E. stoutii skin being more resistant to longitudinally directed stresses, and A. flavidus skin being more resistant to circumferentially directed stresses. The anisotropy in A. flavidus skin is characteristic to published records on elasmobranch and teleost skins. The atypical pattern of anisotropy in hagfish skin may be attributed to its reduced tautness and the extreme knotting and torsional movements readily employed during feeding bouts on oversized prey.