The highlight of the summer was a trip to SeaWorld in San Antonio, Texas. We enjoyed the chance to see some live marine mammals up close. Eric even got to feed some bottlenose dolphins at the Dolphin Cove exhibit.

 
Andrea Glaser joined the lab in the spring of 2005. The goal of her project was to determine if a postcaval sphincter exists in the diaphragms of dwarf sperm whales (Kogia simus). These animals are deep diving cetaceans, and a sphincter at the level of the diaphragm would prevent high pressure blood from returning to the heart during a dive to depth. Sphincters are usually composed of a large proportion of slow-twitch fibers, so Andrea compared the fiber-type profile of the region of the diaphragm surrouding the vena cava to that of the costal region of the diaphragm. She found that the caval region of the diaphragm has an increased percentage of slow-twitch fibers in comparison to the costal region (46% vs. 42%). Andrea presented the results of her study for her Senior Seminar.
 

The spring of 2006 brought Erin Guy to the Dearolf lab. Her project was designed to build off of the work done by Evan Brickell, Eric Traister, and Brandon Thurow on the role of the scalenus muscle in the breathing behaviors of bottlenose dolphins and harbor porpoises. Erin's work demonstrated that, although the scalenus muscles of these two cetaceans are similar in fiber-type profile, only the scalenus of the harbor porpoise is similar in profile to its diaphragm. These results suggest that harbor porpoises recruit both their diaphragms and scalenus muscles to drive their inspiration, while bottlenose dolphins may rely primarily on their scalenus muscles.