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This 24 page Class Notes was uploaded by Sierra on Saturday February 6, 2016. The Class Notes belongs to FNR 251 at Purdue University taught by Rod N. Williams in Spring 2016. Since its upload, it has received 26 views. For similar materials see Ecology And Systematics Of Amphibians, Reptiles, And Birds in Agriculture and Forestry at Purdue University.
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Date Created: 02/06/16
LECTURE 5: ENERGETICS AND METABOLISM THE ECTOTHERMIC LIFE IMPORTANT TERMS Activity Temperature Range Mean Activity Temperature Operative Temperature Homeothermy Acclimation Thermoregulation INTRODUCTION Ectothermic: Reptiles & Amphibians Primary heat source is external Heat is not always available More economical Endothermic: Birds & Mammals Primary heat source is internal Do better in cold environments More expensive I.a. Basic Energetics: Energy Budget Source: HerpetoloEdition. Zug, Vitt, and Caldwell. 2001. I.b. Basic Energetics: Energy Budget Painted Turtle (Chrysemys picta) II. a. Thermal Interactions and Heat Exchange in Ectotherms Heat exchange with the environment occurs via: Radiation Convection Conduction II. b. Thermal Interactions and Heat Exchange in Ectotherms SURFACE AREA VS. VOLUME LENGTH SURFACE VOLUME OF SIDE (cm) AREA (cm ) (cm ) RATIO 1 6 1 6:1 4 96 64 1.5:1 10 600 1,000 0.6:1 20 2,400 8,000 0.3:1 II. c. Thermal Interactions and Heat Exchange in Ectotherms Source: HerpeEdition. Zug, Vitt, and Caldwell. 2001. II. d. Heat Exchange: Aquatic Amphibians Source: HerpetologEdition. Zug, Vitt, and Caldwell. 2001. II. e. Heat Exchange: Terrestrial Amphibians II. f. Heat Exchange: Reptiles II. g. Heat Exchange: Secretive/Nocturnal Amphibian & Reptiles Source: HerpetEdition. Zug, Vitt, and Caldwell. 2001. III. a. Temperature Ranges and Tolerances Examples of Body Temperatures (°C) FNR 251 01/18/2006 nd III. b. Temperature Ranges and Tolerances Active Body Temperature (ATR) varies depending on: Taxa Habitat Season Genetics For most the range is between 27°C and 35°C (few reptiles have ATRs < 20°C) IV. a. Regulation of Body Temperature Regulation of body temperature is due largely due to behavioral adaptations Amphibians (terrestrial) handle regulation differently because of moist skin: Low resistance to water loss Tb largely tracks Te (but a couple of degrees cooler due to evaporation) Reptiles can be exposed to sunlight without excessive water loss IV. b. Regulation of Body Temperature Other physiological / morphological adaptations: Adjustment of blood flow to skin Adjustment of heart rate Color changes Special adaptation seen in leatherback turtles IV . c. Regulation of Body Temperature Spiny Softshell (Apalone spinifera) IV. d. Regulation of Body Temperature Regulation of Body Temperature Through Behavioral Adaptations V. a. Dormancy Dormancy: response to temperature extremes, usually hot and dry in deserts, freezing or below in temperate regions: Scaphiopus active 1 month/year in Arizona Thamnophis for 4 months/year in Manitoba Dormancy can occur in three different forms: Hibernation Freeze Tolerance Estivation V. b. Dormancy 1. Hibernation: Tb largely allowed to track Te, except that metabolic activities slowed even more than “normal” for a given temperature Animals move during hibernation Aquatic hibernation V. c. Dormancy 2. Freeze tolerance: Freezing is lethal to all but a few species (ice crystals destroy cells and extracellular fluid freezes and dehydrates cells) A few species (e.g., Hyla crucifer) are “freeze-tolerant” and survive extracellular freezing V. d. Dormancy 3. Estivation: Animals inhabiting desert and semidesert environments Physiology is not well known Animals retreat to deep burrows with high humidity and moist soils and reduce their metabolism All life process (breeding, etc) are greatly accelerated in these species Review of Terms: Lecture 5 Active Body Temperature (ATR) Conduction, Convection, Radiation Dormancy, Estivation, Freeze Tolerance, Hibernation Ectothermic, Endothermic, Homeothermic Energy Budget Inertial Endothermy Surface Area