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Giovanni Casotti
Department of Biology
West Chester University
Lost? Ask a Turtle: Navigation and Migration in Loggerheads

This case study examines the events surrounding the hatching and migration of loggerhead sea turtles, specifically what mechanisms they use to head towards the ocean (once hatched) and where and how they migrate once in the ocean.  The story is written from the point of view of two hatchlings as they crack through their shells, dig out of the sand, and travel at night along the beach into the ocean.  Once they survive this peril, they make their way to the deep ocean and the North Atlantic current, migrating along it, until decades later the female makes her way back to the same beach to lay her eggs and begin the cycle anew.  The case details how loggerheads navigate these vast distances with seemingly no navigational cues.  The case also explores how other long-distance migratory species such as birds and seals migrate along similar vast distances. Originally written for a Masters-level class in biology called "Case Studies in Physiology," the case could easily be used or modified for senior or even undergraduate level biology-majors course.

The Deep: The Physiology of Decompression Sickness

This case study presents a fictional story in a realistic setting to teach aspects of human cardiovascular and respiratory physiology as they pertain to decompression sickness and its treatment options. Specifically, students learn about the partial pressures of gases in the circulatory system and how they change with depth and altitude. The case relates how Dan and Beth, a couple who operate a charter business for diving expeditions, take six tourists out to dive a shipwreck. When it comes time to ascend, one of the divers cannot be found and Dan must stay behind for the rescue. When he finds the missing diver, there is not enough air left in their tanks to rise slowly and safely decompress. They make it to the surface, but must be airlifted to the nearest decompression chamber for treatment. This case was developed for Masters-level students in biology, but could easily be adapted for an upper-level undergraduate physiology course.