Temperature
Relations (Ch. 5)
Endothermic Animals
Endothermic Animals
• HS = Hm + Hcd + Hcv + Hr - He
• Use behavior + metabolism (Hm) too
Endothermic Animals
• Thermal neutral zone: range temperature
where metabolic rate stable
– Varies by species
Humans?
Endothermic Animals
• Humans tropical: all over planet!
Aquatic Endothermic Animals
• Cold water problem
– Convective heat loss: 20x faster than air (still water) to
100x faster (moving water)
• Solutions? (3)
“Stop the lecture,
you’re killing me!”
Aquatic Endothermic Animals
• Solutions:
• 1) breathe air (avoid gill surface exposure)
• 2) insulate! Blubber (whales), waterproof feathers
(penguins), air-trapping fur (sea otters)
Otter fur: up to 1 million /sq. in.
“Stop the lecture,
you’re killing me!”
Aquatic Endothermic Animals
• Solutions:
• 3) limit heat loss
from appendages
by countercurrent
heat exchangers
Exceptional fishes
• Some fishes regulate temp.
swimming muscles
• Ex, bluefin tuna (fast!)
Exceptional fishes
• Countercurrent heat exchange keeps muscle
temp. constant
– Artery blood cooler in this case…
Surviving Extreme Temperatures
• Reducing Metabolic Rate
– Hummingbirds: enter torpor
(reduce metabolic rate &
lower body temp.)
Months?
Surviving Extreme Temperatures
• Reducing Metabolic Rate (for months)
– Hibernation - Winter (temperate climates)
– Ex, black bear
Avoid summer?
Surviving Extreme Temperatures
• Reducing Metabolic Rate
(for months)
– Estivation - Summer (deserts)
– Ex, lungfishes
– Bury in mud to survive dry
season
Water
Relations (Ch. 6)
Why Water Matters
• Life aquatic (you: 60% water!)
• Solute concentration affects
enzymes
• Water useful: temp. regulation
– HS = Hm + Hcd + Hcv + Hr - He
Water Content Air
• Terrestrial: Most water loss
evaporation (concentration
gradient)
– How express air water content?
Water Content Air
• Relative Humidity:
Water Vapor Density
Saturation Water Vapor Density (x 100%)
– Water vapor density = gm water vapor per unit
volume (meter cubed)
– Saturation water vapor density = water vapor air
potentially holds
• Changes with temperature…..(how?)
Water Content Air
• Note kPa:
pressure unit
(kiloPascals)
• Pascal: metric
unit pressure (1
Newton per sq.
meter)
Vapor pressure….
Water Content Air
• Water Vapor Pressure (WVP):
Partial pressure water vapor.
• Saturation Water Vapor Pressure
(SWVP): Pressure water vapor at
saturation
• Vapor Pressure Deficit (VPD):
SWVP – WVP: drying power air
Water Movement: Soil to Plant
• Water: flows down water potential gradient
Water potential?
Water Movement: Soil to Plant
• Water: flows down water potential gradient.
• Water potential (Psi): capacity water to perform
work (water’s free energy content)
• “Tendency water to move from one place to
another”
– Pure Water Psi = 0 MegaPascals (MPa)
Mega = one million (106)
Psi
• Units: megaPascals
(MPa)
• Psi values negative!
Why?
Mega = one million (106)
Water Movement: Soil to Plant
• Psi values negative! Why?
• Water potential lowered by:
– Dissolved substances (solute potential)
– Attraction water to charged surfaces (matric
potential)
– Pull of evaporation (tension) on water in plants
(negative pressure potential)
• Water potential raised by:
– Pressure (positive pressure potential)
Water Movement: Soil to Plant
• Psiplant = Psisolute + Psimatric + Psipressure
• Psisoil = Psisolute + Psimatric
• Solute potential: salts. Psisolute important
saline soils
• Matric potential (#1 all soils): attraction
water to clays (tiny mineral materials) in
soil
Water Movement:
Soil to Plant
• Concept! If Psiplant < Psisoil,
water flows to plant
Water Regulation on Land
Water Regulation on Land
• Terrestrial organism challenges:
– Evaporative loss (air dry)
– Access replacement water
Recall Energy Balance Equation: HS = Hm + Hcd + Hcv + Hr - He
Now: one for water…
Water Regulation: Plants
• Wip= Wr + Wa - Wt - Ws
•
•
•
•
Wip= Plant internal water
Wr = Roots (+)
Wa = Air (+: humid spots)
Wt = Transpiration
(evaporation from tissues)
• Ws = Secretions (nectar)
Next: roots
Water Acquisition: Plants
• How get water?
• Wip= Wr + Wa - Wt - Ws
– Dry sites: more roots!
Plant from W.
Canada grasslands
Water Regulation on Land: Animals
• Wia = Wd + Wf + Wa - We - Ws
•
•
•
•
•
•
Wia= Animal internal water
Wd = Drinking (+)
Wf = Food (+)
Wa = Absorbed from air (+)
We = Evaporation (-)
Ws = Secretions (-)
Focus: how
get water
Water Acquisition by Animals
• Wia = Wd + Wf + Wa - We - Ws
• Most land animals: get water by eating &
drinking (“preformed water”)
Some watering hole photos...
Water Acquisition by Animals
• Water gained via metabolism (metabolic water)
• C6H12O6 + 6O2  6CO2 + 6H2O
• Water made by aerobic respiration.
Who am I?
Water Acquisition by Animals
• Wia = Wf - We – Ws
Water Acquisition by Animals
• Special adaptations: behavior
• Namib desert (S. Africa)
Lizard flashback
Fog from Atlantic
Water Acquisition by Animals
• Onymacris beetle