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13594407
Mammals
Description
Survival Strategies - Desert living mammals
No tags specified
desert
mammal
survival
camel
water
water loss
water gain
biology
Mind Map by
Adam Heywood
, updated more than 1 year ago
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Created by
Adam Heywood
over 6 years ago
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Resource summary
Mammals
Water Gain
Drinking
Unreliable source
Rainfall unpredictable
Arid = 6 - 10mm, Semi-arid = 50mm +
Flashfloods
Specialist actions to reduce dehydration
Camel
Environment
absorption of moisture in dens or burrows = condensation on cool walls
Diet
Omnivores can obtain 70% of water from insects
Water Loss
REWL (Respiratory evaporative water loss)
Nasal Counter-current exchange
Affected by the surface area
100% saturated air
Delicate structures of the lungs must be damp
Camels do not breath out 100% saturated air
TEWL (Transepidermal evaporative water loss)
Mammalian skin permeable and allows water to pass through
Stratergies for reducing water loss
Concentratation of Nitrogenous waste
Faeces
Can dehydrate faeces - depending on species
Urine
Effective kidney function
Loop of Henle (Counter current multiplyer system)
Can respond to dehydration by concentrating urine
Hyperosmotic to plasma
Ureotylic - production of urea = less water intensive than uric acid, but slightly more toxic
Large Mammals = Endurer
Camel
Can rehydrate 200 liters in 3 minutes
Stores water in the gut to avoid blood dilution
Enhanced nasal counter-current exchange
Heterothermic - when depreived of water can slowly increase body tempr from 35 - 41 C during the day and lose heat during the night
Does not require EWL to reduce body temperature (saves 5 liters of water a day)
Can store urea in tissue when dehydrated
Sand Gazelle
Heart and liver shrinks during times of starvation or dehydration
Smaller hearts = lower metabolism = reduction in water by 1/3
Ostrowski et al, 2006
Lower metabolism = lose heat slower = lowered EWL
Kangaroo
High urine concentration - 3700mOsmol
Lowered rates of metabolism and a lowered body temperature
Reduction in REWL
Circadian locomotory rhythm = many are nocturnal
Lie in cool soil to reduce body temperature in hot days
Vasodilation = lick forarms to cool blood down
Red Kangaroo VS Grey Eastern Kangaroo
Small Mammals = Evader
Kangaroo Rat
Eat a carb rich diet and still stayes hydrated by obtaining water from seeds
Knut Schmidt-Nielson (1951)
Fur lined cheek pouches
Dry faeces reduces nitrogenous water loss
90% of water gained by metabolism, 10% absorbed by dry food
25% of water lost by urine, 5% lost by faeces, 70% lost by EWL
Higher metabolism = lose heat quicker = higher EWL
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