Phenomenon Of Diving Animal Physiology

The phenomenon of diving animal physiology has been known since the time of Aristotle (Berta, Kovacs, and Sumich, 2006). It was not until the early 20th century that the physiology of prolonged marine mammal divers were studied closely, and it has only been recently that scientists have been able to understand the complexities of diving (Berta et al., 2006). The physiology of diving incorporates the study of many different components of how animals function (Costa, 2007). There are many factors that contribute to the phenomenon of diving responses in animals, which include the circulatory system, ecological factors, behavioral instincts, and neurological factors (Withers, 1992). Diving animals all face the same mechanical physiological obstacles,

There are two distinct groups of divers: shallow divers and deep divers (Costa, 2007). The majority of diving vertebrates make shallow, short dives. Sea snakes and crocodiles dive in near shore and only submerge at depths less than ten meters deep (Costa, 2007). Deep divers generally are underwater for extended periods of time (Costa, 2007). Emperor penguins dive at depths between 400 and 500 meters for 4 to 5 minutes to catch prey (Costa, 2007). Elephant seals are another group of animals that dive and travel long distances for periods lasting two to eight months (Costa, 2007). Elephant seals spend approximately 90% of their time at sea submerged, averaging 20 minutes per dive and they spend less than 3 minutes at the surface between dives (Costa, 2007). They feed at depths between 300 and 600 meters and occasionally dive down deeper than 1600 meters (Costa, 2007). Despite the vast differences between all of these animals, they all have evolved mechanisms that function similarly to overcome the physiological strains of diving. The two main diving strains are water pressure that occurs when an animal dives further under water and breath holding (Costa, 2007). These two things effect the mechanical functions of animals, and animals

Mechanisms involved with metabolism, blood flow, and oxygen storage capabilities had to evolve to accommodate diving lifestyles (Costa, 2007). One mechanism is the diving reflex of marine mammals (Heller, Orians, Purves, and Sadava, 1998). This is a highly developed automatic reflex that slows the heart rate of an animal when it submerges underwater (Heller et al., 1998). Humans have a diving reflex that is triggered when a person’s face is immersed in water (Heller et al., 1998). Human’s heart rate automatically slows as soon as a person’s face is completely submerged (Heller et al., 1998). At the end of the dive, heart rate returns at an above-normal rate to flush out the lactate from the muscles back into circulation (Withers, 1992). The period of increased oxygen consumption after a dive is proportional to the amount of oxygen “debt” an animal is after a dive (Withers, 2009). When a marine mammal dives, the majority of the blood flow and available oxygen goes to the animal’s heart and brain (Heller et al., 1998). Scientists have observed that although the heart structure of cetaceans and pinnipeds are very similar to other mammals, one major difference are the enlarged stores of glycogen present in their hearts not found in terrestrial mammals (Berta et al., 2006). Larger stores of