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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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