Honors Theses

Date of Award

2011

Document Type

Undergraduate Thesis

Department

Biology

First Advisor

Glenn Parsons

Relational Format

Dissertation/Thesis

Abstract

Bite force was investigated for nine shark species common to the waters of the Northern Gulf of Mexico using a bite force meter developed for this study. The two primary species examined in this study were blacknose, {Corcharhinus acronotus) and sharpnose (Rhizoprionodon terraenovae) sharks. Other species examined included blacktip (Corcharhinus limbatus), spinner (Corcharhinus brevipinna), finetooth (Corcharhinus isodon), sandbar (Corcharhinus plumbeus), bull (Corcharhinus leucus), tiger (Galeocerdo cuvieri), and bonnethead (Sphyrna tiburo) sharks. Absolute bite force values ranged from 0.9 to 11.79 kg for blacknose, 0.05 to 5.44 kg for sharpnose, 1.36 to 11.34 for blacktip, 1.36 to 5.90 kg for spinner, 1.81 to 3.63 for finetooth, 1.11 to 8.36 kg for bull, and 0.18 to 2.89 kg for tiger sharks. Only one bite force was obtained for bonnethead (0.45 kg) and sandbar (14.45 kg) sharks. Linear regression analysis revealed an increase in absolute bite force and a decrease in relative bite force as size increased for blacknose and sharpnose sharks. Jaw width was the best predictor of bite force in blacknose sharks explaining 8% of the variation. No significant difference in female and male absolute bite force was observed for sharpnose and blacknose sharks. Seventy-two percent of longline captured sharpnose had bite force measurements of 1.0 kg or less whereas only 37.5% of rod and reel captured sharpnose had bite force measurements in the same range. These data could be indications of stress rather than indications of physiological force generating capabilities. Electrically induced, involuntary bite force was consistently higher than voluntary bite force in sharpnose. Overall, it was concluded that sharks do not have a large bite force relative to body size in comparison to other vertebrates. Larger body mass simply allows for a bite force of high magnitude.

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