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How is the sea turtle adpted to meet the requirements for vigorous activity (in water and on land), for prolonged periods and deep diving? The sea turtle requires a respiratory system that is able to support it through diverse depths and distances. Due to sea turtles's excessive breath-hold, the respiratory system must be able to compensate for time elapsed without exhalation. When exhalation does occur, it is brief. The main component that bears the respiratory weight is essentially the lung. The lung, "functions as the major oxygen store and can supply sufficient oxygen for most routine dives (up to 20 mins) to be aerobic" (Lutz,1985). Moreover, the lung almost carries the complete load of respiration in the sea turtle."The respiratory properties of sea turtle blood are particularly well suited to lung-tissue transport during routine brethhold periods, surviving prolonged dives of at least three hours by having a high anaerobic capacity" (Lutz, 1985). This leads to the conclusion that green sea turtles are well adapted for storing and using oxygen stores. "Extended breathhold respiration is therefore the normal mode in sea turtles" (Lutz, 1985).   How does a green sea turtle maximize a high flux of oxygen through a support system of airways? It is the oxygen storage capability of the lung coupled with significant oxygen uptake by the blood. These combining properties help to maximize oxgen influx in the sea turtle during long distance migration and prolonged submergence. "Oxygen uptake by the blood is therefore not hampered by a fall in oxygen affinity as lung oxygen is depleted" (Lutz, 1985). According to Donald C. Jackson, "to meet these needs, the green sea turtle possesses complexly subdivided multicameral lungs with small terminal air spaces through which a high flux of oxygen (at up to 10 times the resting rate) can occur)" (Jackson, 1985). This compartmentalization in lung structure aids the respiratory system in providing substantial support for the green sea turtle during deep-diving. " Support of the airways permits rapid emptying of the lungs during normal breathing and prevents gas trapping during deep diving." (Jackson, 1985). In addition,the green sea turtle compensates for anoxia "by means of vascular shunts and the redistribution of blood away from the lungs during submersion" (Solomon, 1984). Description of Lung Structure and Mechanics The green sea turtle is able to withstand complete anoxia, which is exhibited during its prolonged submergence. On first glance, turtle lung looks like mammalian lung, which is attributable to its complex structure and compartmentalization of air units. Green sea turtle lung has multiple chambers. "When sea turtles breathe, there is an audible rush of air, the neck is arched, elevating the head, and a rapid, audible expiration occurs, followed promptly by a rapid inspiration, and finally a respiratory pause of variable duration held in the end-inspiratory position" (Jackson, 1985. This allows the green sea turtle to breifly come to the surface.         This project was created as a part of a class project in the Animal Physiology class in the Department of Biology at Davidson College E-mail questions to: snreid@davidson.edu   : TOPICS IN ANIMAL PHYSIOLOGY MAIN PAGE