Mechanisms involved in metabolism, blood flow, and oxygen storage capacity have had to evolve to adapt to divers' lifestyles (Costa, 2007). One mechanism is the diving reflex of marine mammals (Heller, Orians, Purves, & Sadava, 1998). This is a highly developed automatic reflex that slows an animal's heart rate when it dives underwater (Heller et al., 1998). Humans have a diving reflex that is activated when a person's face is submerged in water (Heller et al., 1998). The human heart rate automatically slows down as soon as a person's face becomes completely submerged (Heller et al., 1998). At the end of the dive, the heart rate returns to a higher than normal rate to expel lactate from the muscles and put it back into circulation (Withers, 1992). The period of increased oxygen consumption after a dive is proportional to the amount of oxygen “debt” an animal has after a dive (Withers, 2009). When a marine mammal submerges, most 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 is very similar to that of other mammals, one of the main differences is the greater glycogen reserves present in their hearts, not found in land mammals (Berta et al. , 2006). Larger stores than