THINGS THAT MAKE A MARINE MAMMAL A MAMMAL - PowerPoint Presentation

1. THINGS THAT MAKE A MARINE MAMMAL A MAMMALVertebratesWarm bloodedBreath through lungsLive birthMammary glandsIntelligent (Large brains)Hair & Different shapes and sizes of teethMarine mammals are aquatic mammals that rely on the ocean and other marine ecosystems for their existence. They include animals such as seals, whales, manatees, sea otters and polar bears. They do not represent a distinct taxon or systematic grouping, but rather have a polyphyletic relation due to convergent evolution. They are also unified by their reliance on the marine environment for feeding.

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6. A sea otter (Enhydra lutris), a member of family Mustelidae.

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10. Swimming/Movement AdaptationsShape: External/structures will create more drag against swimmingSolutions to reduce dragReduced appendages and tuck them into bodySpindle shapeReduced hair b/c it increases dragExternal ears reduced/internal testis a mammary glandsSmooth skin Large body size: reducing surface area/volume ratio eg: porpoise, humpback, Propulsion: The density of water = ResistanceAnatomical adaptations for movement include:Front Flippers in sea lionsFlukes and hind flippers provide greater speedCetaceans have elastic tissue and blubber in peduncle to provide spring-like propertiesWebbed feet of e.g Polar Bears, sea ottersHumpback whale flippers have “bumps” or tubercle that reduce drag in water and air and increase lift. Humpbacks use their flippers as a biological hydroplane to achieve tight turns, even seen to making tight 180 degree U-turns. The whale utilizes its leading-edge bumps to control lift and avoid stall at high angles of movement at low speeds. Wind turbines modeled after humpback flippers

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12. Echolocation in Whales/Dolphinsound waves are made by phonic lips through blowholemelon directs the out-going sound wavesAfter the echo strikes an object, it is reflected back. The reflected echo are received back by the melon and the fat filled cavity in the lower jawbone for processing to brain where interpretation is madeOdontocetes (toothed whales) developed nasal structures that generate echolocation, enabling them to use sound to locate prey or navigate past obstacles

13. The problems with going deepPressure increases by one atmosphere for every ten meters that you descend into the ocean.  In addition, when a diving animal tries to return to the surface rising too quickly can allow gases that have been dissolved into their blood stream by the high pressures to form bubbles that lodge in critical organs, a condition called “the bends.”    It can be painful, debilitating, and deadly if not treated.Oxygen storage becomes an issue for you and I in less than a minute.  The best free divers in the world can’t hold their breath for longer than five, yet some marine mammals will stay down as long as ninety minutes.Nitrogen narcosis is a condition that results when too much nitrogen is dissolved in the blood.   It can cause a drunken-like condition called nitrogen narcosis.  High levels of nitrogen eventually become toxic to the livers and cause death.The ocean is cold.  Even in the tropics, below 200 meters ocean water temperatures approach freezing. Warm blooded mammals need to maintain a constant body temperature to survive.  In addition, water is a much better conductor than air and removes heat from the body nearly 20 times faster than air.Mammalian bodies float.  Ever tried to swim to the bottom of a swimming pool?  It takes work because most mammals float.

14. Problem 1 Solution: Pressure Air (as a gas) can be compressed, while water (as a liquid) cannot. At sea level a body experiences 14.7 pounds per square inch of pressure (1 atmosphere). For every 10m deep = 1additional atm. Over evolutionary time, most marine mammals have lost their external ears and sinuses. Sea lions and fur seals do have ears, but during a dive their ears will fill with a bloody fluid, forcing any air out. Most marine mammals have lungs that are able to collapse and re-inflate easily. Lungs collapse at 60-70m.They tend to be long and tubular with built-in protective rings to keep valves open. Also, marine mammals tend to exhale right before a dive. They have very muscular and efficient lungs which can exhale up to 90% of the air in their lungs in any give breath (an athletic human can do around 10 %.) Thus, by removing the air from their body, a diving marine mammal has very little problems with changing pressure.  No air, no problem.Problem 2 Solution: Oxygen StorageMarine mammals store oxygen in their blood, and in their muscles rather than in their lungs. Marine mammals have a very high blood to body volume ratio. Marine mammals also have a higher % of red blood cells than most mammals (human = 36%, seals = 50 %.) They are therefore better equipped for oxygen storage. Marine mammals also have a high concentration of hemoglobin in their blood and myoglobin in their muscles. Both of these molecules have a high affinity for oxygen atoms and are used to store oxygen in body tissue. The mass of blood vessels located in the dorsum of the thorax (retia thoracica) have been proposed to function during diving to accommodate for the collapsed lung volume, thereby preventing gross displacement of abdominal organs. When exercising, we say that when humans have run out of oxygen they have gone anaerobic. This means that muscle cells do not have sufficient oxygen to break sugar apart through aerobic respiration. This is very taxing on muscles and leads to soreness and fatigue. In marine mammals, most body organs appear to switch to anaerobic respiration while diving without suffering the same ill effects.

15. Problem 3 Solution: Decompression Sickness “the bends”When human scuba divers come up too quickly from a dive, gases that were dissolved into their blood can come out of solution too quickly and form bubbles inside the blood vessels. These bubbles can get lodged in capillaries and migrate to critical organs, causing pain and possibly organ damage. Marine mammals don’t suffer DCS they exhale before they dive. No air, no problem. In addition, many marine mammals have an extensive “net” of blood vessels feeding into their brain. Its known as the “retia mirabilia,” and one of its functions is capturing bubbles that may form in the blood stream.Problem 4 Solution: The ColdWater dissipates heat from the body much faster than air. A person who falls in water near the freezing point will be hypothermic within a few minutes, yet marine mammals dive to depths where the temperatures approach freezing.The most obvious way that marine mammals stay warm is that they tend to be large and rather “sausage shaped.” This shape gives them a low surface area to volume ratio. Per unit volume, there is less skin exposed to cold moving water. Marine mammals also have a lot of blood relative to their body size. Water has a high heat capacity and does a nice job of maintaining body temperature.  Most marine mammals have a thick layer of fat know as “blubber.” This fat layer also serves as calorie storage for marine mammals that undergo long periods of fasting. Smaller marine mammals tend to have highly insulated layers of fur. The extreme example of this is the sea otter. Sea otter fur is two layers thick, and very effective at trapping air to aide in insulation. Sea otters may have as many as one million hairs per square inch. That’s ten times as many hairs as the average human has on their whole head.

16. Problem 5 Solution: BuoyancyNo part of a mammal is more buoyant than the air in their lungs. For marine mammals, the key to reducing this buoyancy is to exhale before diving.  Removing oxygen from the lungs makes animals slightly negatively buoyant.  In order to save energy diving, marine mammals will often sink in a “sleep like state” during the decent of a long dive.Marine diving championsthick billed murres – weighing only a pound or two, they can dive up to 100 meterselephant seals – to 1500 meters, over 60 minutes, spend 90% of time at sea divingemperor penguins – up to 500 metersleatherback sea turtles – up to 1200 meterssperm whales – up to 2032 meters, regularly staying down for 90 minutesCuvier’s beaked whales – up to 2992 meters, stayed underwater 138 minutes

17. Adaptation for survival in cold waterIn order to preserve heat in the cold water of the deep, it is more beneficial to have a larger volume compared to your body surface, so there are fewer opportunities for heat loss. This helps to explain why marine mammals tend to be so large, as it is beneficial for them to have the smallest relative surface area in contact with the water.The second main way whales stay warm is blubber. Although fur is a good insulator for terrestrial mammals, it would not be as successful for whales for a couple of reasons. Fur works as an insulator because it traps an insulating layer of air: however, the atmospheric pressure beneath the surface waters causes the air to compress and lose its insulating power. Therefore, whales do not have a protective fur coat like many land mammals or seals and polar bears, and rely instead on their thick blubber to insulate their bodies in cold water. This blubber allows for a very smooth external surface, also reducing hydrodynamic drag. Another way whales reduce both heat loss and drag is to internalize their genitalia, instead of it being external like most terrestrial mammals.

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19. Adaptation for survival in warm waterWhat if whales overheat because they are swimming fast, are surface active, are pregnant, or are in warmer water. Whales do not have sebaceous glands and cannot sweat like we can to cool off, so they need a different strategy to be able to dump excess heat...and in order to shed heat, there must be a way to bypass the blubber layer. They use thermal windows that lack blubber and are not well insulated. These areas include flippers, dorsal fins, and their flukes, each relatively thin and highly vascularized.  However heat lost through the thermal windows is decreased by “counter-current heat exchange”One of the issues with these areas is that the blood returning from them is cold and could potentially cold shock the heart. This is prevented by another great adaptation—a system called counter-current heat exchange. The arteries and veins in these tissues are very close together but the blood flows in different directions allowing heat to transfer across membranes. So the heat in warm blood that is leaving the heart will heat up the cold blood that is headed back to the heart from the extremities. This means that the heart is always being pumped with warm blood and it decreases the heat lost to the water in those thermal windows.

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