Ecology Section II: Organismal Ecology; Water

How do camels conserve water?

- thick coat provides insulation and reflects sun, reducing need for evaporative cooling. - fat stored in hump as source of metabolic water. - thick, concentrated during + extremely dry feces.

Adaptions for water conservation in plants include:

- thick, waxy leaves - few stomata - periodic dormancy; dropping leaves in response to drought - root development

For most organisms, what three functions are all connected?

- water regulation - thermoregulation - energy budgets

Adaptions for water conservation by animals:

- waterproof outer coverings - concentrated urine/feces - behavioral modifications to avoid stress - water gained via metabolism

For organisms that use evaporative cooling.....

.....Thermoreglation is closely linked to water regulation.

What are the two major challenges terrestrial organisms face?

1) evaporative loss to environment. 2) limited access to replacement water.

What is the water content of most organisms?

50-90%.

water regulation equation for terrestrial animals

Wia = Wd + Wf + Wa - We - Ws Wia = internal water Wd = intake by drinking Wf = intake by food Wa = absorbed from air We = loss from evaporation Ws = lost by secretion (urine, feces)

Water regulation equation for Terrestrial Plants

Wip = Wr + Wa - Wt - Ws Wip = plant's internal water Wr = intake from soil via roots Wa = absorbed from air Wt = lost by transpiration Ws = lost with secretions; nectar

What is the main avenue of water acquisition in terrestrial plants?

Wr; water taken up from soil by roots.

What is the main avenue of water loss in terrestrial plants?

Wt; water lost by transpiration.

Hypo-osmotic =

bony marine fish; body fluid (water) > external env. body fluid (salt) < external env. *drink seawater *excrete sal through gills *excrete little/no urine, concentrated w/ salt.

WCG (water concentration gradient) =

difference in water content between two media or between and organism and it's surroundings.

Osmosis =

diffusion of water across a semi-permeable membrane. increased concentration gradients = increased osmotic pressures.

Hyperosmotic =

freshwater fish; body fluid (water) < external env. body fluid (salt) > external env. * never drink * excrete large amounts of dilute urine * consume sodium

Water moves....

from high to low concentrations (down gradient).

Most marine mammals are _______.

hypo-osmotic; produce highly concentrated urine to excrete salt.

Lower concentration of water vapor in air =

increased WCG from organism to air; evaporation.

Isomotic

sharks, rays; body fluid (salt/water) ~=~ ext. env. *little energy required

Diffusion =

Movement of molecules (H2O) down a concentration gradient.

What is the main avenue of water acquisition in terrestrial animals?

Intake by drinking and food; Wd/Wf.

What is the main avenue of water loss in terrestrial animals?

Water lost by evaporation; We.