PNB 2250 Lecture Notes - Lecture 26: Burping, Glycogen, Chondrichthyes
31 Oct 2016
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Buoyancy: an upward force exerted by a fluid that opposes the weight (gravity) of an immersed object, the force is proportional to the weight of the fluid displaced by the object. Which is affected by the object shape. If an animal is heavier than the water that is displaces, it will sink and must expend energy to float. If the animal has the same density as water, it floats and has natural buoyancy. Density the same or less than 1gm/ml: density isn"t an issue for terrestrial animals unless they swim or fly. Options: swim to float, fins provide lift during movement. Like the lift due to airplane wings: fins cant be used for anything else, energetically expensive. No sunlight, little food, very cold: alter physical density. Ions like iron, calcium, rely on the kidney: develop a swim bladder. Increases diversity of fish forms: alter content of liver oils.
