Lets explore this relationship between hibernation and bodysize, by considering stored energy and the rate of energymetabolism (utilization). Here, you will calculate whetherhibernation is necessary by comparing a 1200 pound polar bear and a1.5 pound grey squirrel (like those living here in Columbus). Wecan compare how long each could survive during a winter fast ifthey used only body fat as their energy source, and do nothibernate (which requires a drop in metabolism below the BMR). Theweight-specific Basal metabolic rate (BMR) of mammals is 4.46M-0.30 when expressed in units ofmLO2consumed per gram of body tissue perhour and (importantly) weight is calculated ingrams. For this simple estimate, you may use BMR, but keepin mind that small animals have a larger increase in metabolismwith temperature than large animals. Calculate how long each animalcould survive on stored fat equal to 20% of its total body weight(this is a fairly reasonable fat amount found in both squirrels andbears in nature). Make sure you keep all units very clear duringthis calculation, there are many steps.
Potentially useful information:
The value of energy content of fat is 9.3 kCal per gram of fatand 2.0 L of O2 are consumed per gram of fatmetabolized. There are 5280 feet in a mile, and 1.0 foot = 0.3048meters. One calorie = 4.184 joules. One pound (lb) = 454 grams andone ounce is 28.375 grams.
Lets explore this relationship between hibernation and bodysize, by considering stored energy and the rate of energymetabolism (utilization). Here, you will calculate whetherhibernation is necessary by comparing a 1200 pound polar bear and a1.5 pound grey squirrel (like those living here in Columbus). Wecan compare how long each could survive during a winter fast ifthey used only body fat as their energy source, and do nothibernate (which requires a drop in metabolism below the BMR). Theweight-specific Basal metabolic rate (BMR) of mammals is 4.46M-0.30 when expressed in units ofmLO2consumed per gram of body tissue perhour and (importantly) weight is calculated ingrams. For this simple estimate, you may use BMR, but keepin mind that small animals have a larger increase in metabolismwith temperature than large animals. Calculate how long each animalcould survive on stored fat equal to 20% of its total body weight(this is a fairly reasonable fat amount found in both squirrels andbears in nature). Make sure you keep all units very clear duringthis calculation, there are many steps.
Potentially useful information:
The value of energy content of fat is 9.3 kCal per gram of fatand 2.0 L of O2 are consumed per gram of fatmetabolized. There are 5280 feet in a mile, and 1.0 foot = 0.3048meters. One calorie = 4.184 joules. One pound (lb) = 454 grams andone ounce is 28.375 grams.
