Meeting Abstract
Sharks, which are uniformly carnivorous, have guts optimized for digesting a high-protein diet. Omnivores, on the other hand, also digest plant material, and thus, face the difficulty of digesting foods that are low in protein and lipid, and are sheathed in rigid cell walls. Interestingly, the bonnethead shark (Sphyrna tiburo) is known to consume copious amounts of seagrass as juveniles (62% of gut content mass in some populations), yet maintains a gut that morphologically reflects its carnivorous ancestry. Hence, in comparison to other sharks, juvenile bonnethead sharks may have adjusted their gut function to utilize plant material. The objective of this project is to investigate S. tiburo digestion to understand whether they can digest seagrass. The activities of various digestive enzymes, such as amylase, cellulase (including beta-glucosidase) and sucrase, were measured along with the concentrations of short chain fatty acids in the guts of juvenile bonnetheads. Digestibility of carnivorous, omnivorous, and seagrass diets was also measured in captive adult bonnetheads, and data analysis is in progress. This project could provide groundbreaking evidence that sharks, animals that were previously thought to be solely carnivorous, can benefit from the digestion of seagrass.
