VertZooNotesDrei - 3rd Part Vertebrate Biology Notes...

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3 rd Part Vertebrate Biology Notes Control of Body Temp This is an important capability as the rate of biological processes affected by temperature. The terms Poikliothermic and homeothermic refer to how an organism’s body temperature varies over time. Poikliotherms vary with time and homeotherms maintain a constant body temperature regardless of time. Ectotherms and endotherms are organisms that maintain their body temperature through either the effect of the environment or via internal metabolic processes. Fish, amphibians and reptiles are ectotherms while Mammals and birds are endotherms. Ectotherms -10-14% lower metabolic rate. -Need less food. -Body size unrestricted -20% of salam., 17% of anurans less then 1g -60% of salam., 50% of anurans less then 5g -allows for increased surface to volume ratio. -Body shape more flexible -elongate forms -dorsoventrally or laterally flattened -fill ecological niches not open to endotherms Endotherms - High metabolic rate -require more food -Restricted body size (3 grams smallest) -Size limited by surface to volume ratio -body shape restricted -no elongation -no flattening Ectothermy and endothermy are not mutual exclusive. Pythons can produce heat by coiling around eggs, roadrunners lower body temp at night and raise it during morning. Bats lower their body temp during the day and raising it as night falls by moving closer to the roost entrance. Ectothermy is pleisomorphic and just as effective as endothermy. Comparisons Ectotherms -Ancestral -relax homeostasis and less energy needed -Convert more energy to biomass -assimilation 30-90% of food consumed -key positions in ecosystems for energy flow -slower CNS response -slower response times -restricted. Must curtail metabolic activity in cold conditions -physical world has greatest impact Endotherms -derived -maintains homeostasis and requires more energy -90% of energy turns to heat -<10% assimilated -Feed on ectotherms -faster cns response and information processing -more forceful, rapid contractions and faster response times -can live in wide range of thermal conditions
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-biological interactions have greater impact Others aspects of ecology and behavior that are affected -Diet and what are eaten, feeding time, insulation, social behavior and choice of shelters. -endotherms eat energy rich foods (such as meat) and specialized digestively for a certain food source. They also eat more food then ectotherms. Fur and feathers employed in trapping heat close to the body. They have social behavior for food acquiring and warmth (flying squirrels nesting in groups during winter). Endotherms are active all the time while ectotherms are limited by temperature as to when they are active. Control of body temperature by ectotherms Behaviorally - movement between sun and shade used. This is important in lizards. They also use ground to help heat. They orient themselves so as to get as much sun on their body as possible. Body contour can flatten and increase surface area. Color change can be used to increase amount of heat acquired, lizards being the best at this. They’re all limited to a 4-10C activity range.
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This note was uploaded on 04/30/2009 for the course BIO 400 taught by Professor Rebar during the Spring '09 term at Edinboro.

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VertZooNotesDrei - 3rd Part Vertebrate Biology Notes...

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