1	ANIMAL ADAPTATIONS TO SEMIARID / ARID ENVIRONMENTS
2	WHAT WAYS DO ANIMALS GAIN AND LOSE WATER?
3	WATER GAIN
4	WATER GAIN Drinking Food Absorption Ex., amphibians Aquaporins
5	WATER GAIN Drinking Food Absorption Metabolism (metabolic water) Ex., kangaroo rat
6	WATER GAIN Drinking Food Absorption Metabolism (metabolic water) C₆H₁₂O₆ + 6 O₂ 6 CO₂ + 6 H₂O glucose oxygen carbon dioxide water ~ 6g water produced for every 1g glucose metabolized
7	WATER LOSS Evaporation Partly a function of surface area Humans epidermis ~2 m² Lose ~450 ml/day (~20% of intake) @ 30⁰C (86⁰F), lose 22mg/cm²/h Animal Water Loss (mg/cm²/h) African antelope 3.24 Poorwill 0.86 Desert mouse 0.66 Lizard 0.10 Scorpion 0.02
8	WATER LOSS Evaporation Respiration Humans ~350 ml/d (~15% of daily intake)
9	WATER LOSS Evaporation Respiration Excretion Urine Human: ~1,500 ml/d (~58% of intake) Feces Human: ~200 ml/d (~8% of intake)
10	WHAT ARE WAYS ANIMALS COPE WITH LOW WATER AVAILABILITY?
11	PHYSIOLOGICAL ADAPTATIONS Kidney structure & function Type of excretory products Kidney structure Storage Salt secretion Protective coverings Tolerance
12	Excretion Why urinate? Elimination of excess water & salts Elimination of metabolic wastes
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14	3 Main Nitrogenous Wastes (Excretion) 1. Ammonia Highly toxic Highly water soluble 2. Urea Less toxic (100,000 less toxic than ammonia) Excretion requires 10 times less water Energy often required (4 ATP per molecule) Concentration up to 25 times that of plasma 3. Uric Acid Non toxic Excretion requires 50 times less water Energy intensive (8 ATP per molecule) Concentration up to 3,000 times that of plasma
15	Excretion Ammonia Solution = flushing Highly toxic Highly water soluble (requires lots of water)
16	Excretion Urea Solution = detoxification Urea ~100,000x less toxic than ammonia Requires less water to excrete
17	Excretion Uric acid Solution = insolubilization Requires little water to excrete Can be concentrated within amniotic eggs
18	Kidney Structure
19	Kidney Structure Structure length of Loop of Henle, ability to concentrate urine Human Excrete ~58% of daily water intake ~25x concentration of plasma Kangaroo rat Excrete ~22% of daily water intake ~3,000x concentration of plasma
20	Storage Ex., camels Up to 2 weeks without drinking Drink up to 40 gal Held as interstitial fluid
21	Salt Secretion Mammals (some) Nasal passages dry out & contain salt secretions Absorbs moisture exhaled during respiration
22	Salt Secretion Birds & reptiles Presence of salt glands Excrete excess salts
23	Protective Coverings Scales – reptiles Exoskeleton – arthropods
24	Tolerance Great Basin Spadefoot Toad Estivates 7-8 months Primarily nocturnal Emerge after rainfall Can lose 48% of its weight in water Eggs can develop in 2-3 days; tadpole to adult in 2-3 weeks
25	WHAT ARE WAYS ANIMALS COPE WITH TEMPERATURE EXTREMES?
26	Ectothermy vs. Endothermy Ectothermy Spend less energy on temperature regulation and more energy on growth and reproduction. Require less energy to survive and can therefore spend less time foraging. Are incapable of sustaining high expenditures of energy. Are unable to cope well with over heating or under cooling thus their active temperature range is small.
27	Ectotherms Heliothermy Warm themselves mainly by sunlight. Control the amount of sunlight they receive by moving in and out of the sun. May darken or lighten their skin pigment to absorb more or less sunlight.
28	Ectotherms Thigmothermy Derive heat from warm surfaces (ie. warm road). Often flatten themselves against warm surfaces to heat themselves up
29	Ectothermy vs. Endothermy Endothermy Can regulate body temperature which allows them to live in colder environments Can sustain a high metabolic rate even at low temperature if food is available Requires more energy than other similar sized ectotherm. To stay cool, lose heat through evaporation (i.e., sweating, or panting).
30	Coping with Temperature Extremes Ectothermy vs. Endothermy Evasion Burrowing Nocturnal activity Estivation
31	Coping with Temperature Extremes Endothery & ectothermy Evasion Evaporative cooling Lose ~580 cal heat/g H₂O evaporating from skin Sweat Lick fur Pant Defecate on legs Fluff feathers/fur
32	Coping with Temperature Extremes Endothery & ectothermy Evasion Evaporative cooling Alter metabolism Torpor Ex., hummingbirds
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53	3 Main Nitrogenous Wastes (Excretion) 1. Ammonia Highly toxic Highly water soluble 2. Urea Less toxic (100,000 less toxic than ammonia) Excretion requires 10 times less water Energy often required (4 ATP per molecule) Concentration up to 25 times that of plasma 3. Uric Acid Non toxic Excretion requires 50 times less water Energy intensive (8 ATP per molecule) Concentration up to 3,000 times that of plasma