Year

2022

Season

Fall

Paper Type

Master's Thesis

College

College of Arts and Sciences

Degree Name

Master of Science in Biology (MS)

Department

Biology

NACO controlled Corporate Body

University of North Florida. Department of Biology

First Advisor

Dr. Maria Laura Habegger

Second Advisor

Dr. James Gelsleichter

Third Advisor

Dr. Kelly Smith

Department Chair

Dr. Cliff Ross

College Dean

Dr. Kaveri Subrahmanyam

Abstract

The integument plays essential roles in the structural support, protection, and hydrodynamic capability among fishes. Most shark skin research has been done on the external epidermal layer containing the dermal denticles, while the larger dermis layer has been mostly ignored. The dermis layer in sharks is composed of two layers, the upper stratum laxum and the lower stratum compactum, holding supportive collagen and elastin fibers. There may be morphological and compositional differences in the dermis layers across various species of sharks, although the extent of such is unknown. These potential differences may be represented by various dermal thicknesses and different fiber compositions and could relate to different shark swimming modes and ecologies. The goal of this study was to thoroughly characterize and describe the dermis layer among three shark species, Ginglymostoma cirratum, Sphyrna mokarran and Isurus oxyrinchus, representing various swimming modes. Histological characterizations were performed at sixteen locations along the body of each shark; variables such as dermal thickness and abundance of collagen and elastin were quantified among others. Consistent with previous studies, this study found a thicker stratum compactum compared to the stratum laxum at all locations across species. Additionally, results showed patterns of increased elastin and decreased collagen in the thunniform swimmer, I. oxyrinchus, and patterns of decreased elastin and increased collagen in the anguilliform swimmer, G. cirratum. As collagen is a measure of stiffness, these results may challenge the traditional swimming modes based on stiffness parameters. Additionally, the dermal layer was thinner in the flank region of thunniform and carangiform swimmers, especially in I. oxyrinchus, supporting previous research of a highly flexible flank region in the mako shark. The results of this research will contribute novel information on the relationships between dermis fibers and ecomorphologies with potential implications on the biomechanics of aquatic locomotion.

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