1 chapter 7 animal adaptations to the environments
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Chapter 7 Animal adaptations to the Environments
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Challenges of terrestrial animals
• Temperature
• Moisture
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Surface area-volume ratio
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Adaptation to temperature
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Adaptations to temperatures
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Body Temperature Regulation
• Ectotherms– Rely mainly on external energy sources.
• Endotherms– Rely heavily on metabolic energy.
• Poikilotherms– Body temperature varies directly with
environmental temperature.
• Homeotherms – maintain a relatively constant internal
environment
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Temperature Regulation by Ectothermic Animals
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Behavioral thermoregulation
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Acclimatization: long-term temperature regulation
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Temperature Regulation by Endothermic Animals
• Thermal neutral zone is the range of environmental temperatures over which the metabolic rate of a homeothermic animal does not change.– Breadth varies among endothermic
species.
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Countercurrent heat exchange
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Surviving Extreme TemperaturesInactivity– Seek shelter during extreme periods.
Reducing Metabolic Rate Hummingbirds enter a state of torpor when food is scarce and night
temps are extreme.
Hibernation - Winter Estivation – Summer
Migration
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Adaptation to water
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(II) Water Regulation on Land
• Terrestrial organisms face (2) major challenges:– Evaporative loss to environment.– Reduced access to replacement water.
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Water Regulation on Land
• Wia= Wd + Wf + Wa - We - Ws
• Wia= Animal’s internal water
• Wd = Drinking
• Wf = Food
• Wa = Absorbed by air
• We = Evaporation
• Ws = Secretion / Excretion
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Water Regulation on Land
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Water Acquisition
• Most terrestrial animals satisfy their water needs via eating and drinking.– Can also be gained via metabolism
through oxidation of glucose:• C6H12O6 + 6O2 6CO2 + 6H2O
– Metabolic water refers to the water released during cellular respiration.
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Water regulation of terrestrial animals
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(III) Water Movement in Aquatic Environments
• If two environments differ in water or salt concentrations, substances will tend to move down their concentration gradients.– Diffusion
• Osmosis: Diffusion through a semipermeable membrane.
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(III) Water Movement in Aquatic Environment
• Isomotic: Body fluids and external fluid are at the same concentration.
• Hypoosmotic: Body fluids are at a higher concentration than the external environment.
• Hyperosmotic: Body fluids are at a lower concentration than the external environment.
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lossGain
Gainloss
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(IV) Water and Salt BalanceWater regulationof hyperosmoticanimals
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Hypoosmotic animals
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Mitochondria-rich cell
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