Form and Function of Hearts and Toes

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As a comparative physiologist, I have focused my research on the role of phylogenetic processes in shaping an animal for its environment by tracking the functional morphology of organ systems across the animal kingdom or studying the physiology of animals at the extremes of the biological range of exercise and diving capabilities. In respect to functional morphology of organ systems, I will be looking at the heart of sea turtles, arguably the most active of all turtles, and emus which raise their heads way above their hearts and have to compensate for gravitational effects. Why are these animals interesting? Our view of evolution of the reptilian heart, based on morphological and paleontological phylogenies, has been upset by the advent of molecular phylogenies. Turtles have lost their place at the base of the phylogeny and are now placed among the snakes and lizards. I have researched lizard hearts and now propose to investigate heart structure and function in sea turtles, looking for anatomical and physiological relationships by investigations of the living heart by trans-oesophageal ultrasound and magnetic resonance imaging. A head held high above the heart means that the heart has to pump much harder to create a high blood pressure so the blood vessels don't collapse and stop flow. All long necked animals have large hearts suggesting they can pump at high pressures but, to date, nobody has ever recorded pressure from a behaving animal. I propose to record arterial blood pressure from unrestrained emus and correlate it to the position of the head above or below the heart. In the duck diving field, one of the most intriguing aspects is that nobody knows the actual energetic cost of the dive components (descent, holding at the bottom to feed and ascent). Work done is force multiplied by distance moved so descent and ascent are easy but, at the bottom, ducks continue paddling to hold their position. Hence, no distance moved, no work done but the ducks look to be working hard. We are proposing to model the work done during diving by measuring the work done by moving the feet through the water during paddling, so we have a distance moved! This research will be indispensable to future studies of the eco-physiology of diving.