Why are most marine mammals able to hold their breath for so long?
Some marine mammals are better than others when it comes to holding their breath for long periods. There are several reasons for this ability: 1) Most marine mammals are larger than most terrestrial mammals, and large animals carry more oxygen and use less oxygen per kilogram than smaller animals. 2) Besides carrying more total oxygen by being large, marine mammals tend to carry more oxygen per kilogram than terrestrial mammals because they tend to store most of it in the blood and muscles, rather than in the lungs. (The champion marine mammal divers such as the sperm whale and the elephant seal carry most of their oxygen in their blood and almost nothing in their lungs.) 3) Marine mammals tend to reduce the amount of energy that they use (and hence the amount of oxygen that they need) when they dive through a process called the dive response. This process involves lowering their body temperature (hence saving energy needed to keep the body warm) and the amount of work performed by the
