It focuses on how water is being regulated by both plants and animals.

1. 6.2

6. WATER SOURCES:
Wd = Drinking
Wf = Food
Wa = Absorbed from the air
AVENUES OF WATER LOSS:
We = water lost by Evaporation
Ws = Secretion / Excretion

7. 𝐖𝐞
𝐖𝐚
𝐖𝐝 𝐖𝐟
𝐖𝐬
(water acquisition
through absorption)
(water acquisition
through drinking &
food)
(water loss through
evaporation)
(water loss through
secretions)

8. WATER SOURCES:
Wr = Water taken by the roots
Wa = Water absorbed from the air
AVENUES OF WATER LOSS:
Wt = Water lost by transpiration
Ws = Water lost by secretions

9. 𝐖𝐬
𝐖𝐚
𝐖𝐭
𝐖𝐫
(water acquisition
from moist air)
(water loss through
transpiration) (water loss through
secretions such as
nectar)
(water acquisition
by roots)

11. Their need of acquiring
water depends upon their
environment.
Moist Environment
(forest)
Arid Environment
(desert)

12. Acquisition of Water in
moist climates through…
Drinking
Food
Air

13. Acquisition of Water in
dry climates through…
Metabolic
Water
Air Moisture

14. Some desert animals
acquire water in unusual
ways.
(Lepidochora)
(Onymacris
Unguicularis)

15. Lepidochora
Collects
moisture by
digging trenches
on the face of
sand dunes to
condense and
concentrate fog.

17. Onymacris
Unguicularis
Collects
moisture by
orienting its
abdomen
upward.

19. Other Mechanism
WATER can also be gained via
metabolism through oxidation of glucose:
C6H12O6 + 6O2  6CO2 + 6H2O
METABOLIC WATER refers to the water
released during cellular respiration.

20. Kangaroo Rat
In every 100 g of barley
that it eats, it gains 60 ml of
water. 6 mL of it is the
absorbed water that can be
driven off by drying while
the remaining 54 mL of
water is released as the rat
metabolizes the
carbohydrates, fats, and
proteins in the grain.

23. Plants acquire
water through…

24. Plants in dry climates
grow more roots than do
plants in moist climates.
Moist Sites Dry Sites

25. In dry climates, plant roots tend to
grow deeper in the soil and to constitute a
greater proportion of biomass.
In deserts and semiarid grasslands, roots may
account for up to 90% of total plant biomass while
in coniferous forests, roots only constitute 25%.

26. Root
Development
R. Coupland and
R. Johnson (1965)
compared the rooting
characteristics of
Artemesia frigida in
the temperate
grasslands of western
Canada.

27. Soil moisture influences the extent of root
development by Artemesia frigida.

28. OBSERVATION:
Microclimate affects
root development.
Deeper roots often
help plants from dry
environment extract
water from deep
w/in soil.

29. Y.M. PARK studied two common
grasses that grow in Japan
Digitaria adscendens Eleusine indica
Grows on coastal
sand dunes
Does not grow on
coastal sand dunes

30. Park’s Investigation on Root Growth
Park planted both
grasses into tubes filled
with sand from coastal
dunes and kept them
unwatered for 19 days.
He noticed that the root
mass of Digitaria increased
almost sevenfold over the 19
days of no watering, while the
roots of Eleusine increased
about threefold.

32. Leaf Water Potential
If a plant has lower root mass, its
leaf water potential decreases.
If a plant has higher root mass, it
maintains a higher leaf water
potential.

35. Waterproofing
Many terrestrial
plants and animals
cover themselves
with a fairly
waterproof “hide”
impregnated with a
variety of
waterproofing
waxes.

36. Neil Hadely & Thomas Shultz studied
the waterproofing of 2 tiger beetles in
different microclimates.
Cicendela oregona Cicendela obsoleta
(active in
spring & fall)
(active in
summer)

38. Waterproofing Cuticles
of Tiger Beetles
• The waterproofing cuticles of
terrestrial insects are provided by
hydrocarbons : Lipids & Waxes
“The lesser the hydrocarbon content,
it is less waterproofed. The greater the
hydrocarbon content, it is more
waterproofed.”

40. Other Water-Conserving
Mechanisms of Animals
Producing concentrated urine or
feces with low water content
Condensing and reclaiming the
water vapor in breath
Restricting activities to times and
places that decrease water loss.

41. Plant Water Conservation
“How much water a plant can
conserve depends in part on its leaf
relative to its root area or length.”
Plants with more
leaf surface per length
of root lose more
water.

42. Plants reduce leaf area by
dropping of leaves.
Ocotillo
(produces leaves in
times of rain)
(reduces leaf area
to zero in times of
drought)

43. Temporary Wilting
It is a water-
conserving mechanism
that reduces leaf area
exposed to solar
radiation by 55% and
leaf temperature up to
4⁰ to 5⁰C.

44. It decreases
the rate of
transpiration by
30% to 50%, which
is a substantial
water savings.
After 8
minutes, wilting
reduces the surface
area.

45. Other Plant Adaptations that
Conserve Water
• Plants with thick leaves
• Few stomata on leaves
• Structures on the stomata that blocks
the movement of water
• Dormancy during times when moisture
unavailable
• Alternative water-conserving for
photosynthesis.