Chapter 30 Water, Salts, and Excretion at Work: Mammals of Deserts and Dry Savannas

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review questions

  1.  Temperature Regulation in the Heat: Keeping Cool
  2. Figure 30.1 The rate of evaporative water loss experienced by mammals exposed to heat stress depends strongly on their body size
    1. Within a group, total rate of evaporative water loss is an allometric function of size
    2. Evaporation to maintain a constant body temperature increases rapidly with body size under hot desert conditions.
  3. Keeping Cool: The Importance of Body Size
    1. Large body size is a physiological advantage in terms of water costs
  4. Effect of Body Size
    1. Small animal
      1. High water loss/unit body mass
    2. Large animal
      1. Low water loss/unit body mass
  5. Adaptations to Thermal Environment
  6. Coexisting species are diverse in their relations to drinking water
    1. Drinking water independent
    2. Drinking water dependent 
  7. Figure 30.2 Common wildebeests are drinking-water-dependent antelopes that seek shade
  8. Figure 30.3 Grant's gazelles are drinking-water-independent antelopes noted for their indifference to sun or shade
  9. Figure 30.4 The annual migration of drinking water dependent zebras and wildebeests in the Serengeti ecosystem
  10. Fig 30.6 Experimental water budgets of wildebeests and oryxes
    1. All species of large herbivores require considerable amounts of preformed water
    2. Oryx are water independent and require less water
  11. Figure 30.7 The moisture content of 'dry' grass varies with time of day or night
  12. Figure 30.9 The desert beetle Onymacris unguicularis collects water from fog in the Namib Desert
  13. Figure 30.10 Oryxes in deserts often exist on dead, dry grasses and the leaves of water-stressed bushes and trees
    1. Oryxes conserve water exceptionally well by several mechanisms
  14. Figure 30.11 Average body-core temperatures of free-living Arabian oryxes over the 24-hour day
  15. Table 30.2
  16. Advantages of being large in hot environment, e.g., camel.
  17. Changes in Core Body Temperature
    1. When unwatered, camel can tolerate increase in body temperature up to 41degrees C. (SN Fig. 7.23)
    2. Their body temperature goes up and down by about 7 degrees C,
    3. Oryxes undergo similar changes (HWA Fig 30.11)
  18. Figure 30.11 Average body-core temperatures of free-living Arabian oryxes over the 24-hour day
  19. Advantages of being large in hot environment, e.g., camel.
  20. Advantages of being large in hot environment, e.g., camel.
  21. Camels can drink more than third of body weight at a time.

 

 

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