Theses and Dissertations

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Defense Date

12-2013

Document Type

Thesis - NSU Access Only

Degree Name

M.S. Marine Biology

Department

Oceanographic Center

First Advisor

Robin L. Sherman

Second Advisor

Richard E. Spieler

Third Advisor

Alois Lametschwandtner

Abstract

Both Elasmobranchii and Acipenseriformes have a spiral intestine, developed by the intestine folding inward and twisting upon itself. A comparative analysis of the digestive system of examples of Subclass Elasmobranchii (sharks and rays) to Order Acipenseriformes (sturgeon and paddlefish) was conducted through gross dissection and scanning electron microscopy (SEM) analysis. Urobatis jamaicensis, Acipenser baerii, and Polyodon spathula were used due to accessibility. Gross dissection analysis yielded that the acipenserids have a columnar spiral valve with 8 infoldings, and U. jamaicensis has a posterior spiral valve with 13 infoldings. SEM analysis showed angiogenesis, where visible, occurred inversely with age in all species. More venous vessels were present than arterial vessels in the outer layers of the intestine, the muscularis and serosa, while the majority of the arterioles were found in the mucosa and submucosa.

The vascularization pattern of the spiral valve in U. jamaicensis showed a diamond branching pattern on the surface anteriorly and posteriorly with a lateral drainage system at the midsection. Only the lateral drainage system was found in A. baerii and P. spathula. The daughter arterioles and venules to the intraintestinal artery and intraintestinal vein coincided with the turns present in the spiral valve of each species. This study suggests A. baerii and P. spathula are sister taxa and do not share a direct common ancestor with U. jamaicensis based on similarities and differences between the spiral valve vasculature.

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