3. Adaptation needs to outweigh the needs of the body
more than the benefits of the body
4. Balances
The natural environment is a system of balances
Law of thermodynamics
Input and output should be equal
When will there be an imbalance?
9. Advantages of endothermy
Longer vigorous activities than ectotherms
Sustained activity is only possible in endotherms
Thermal problems living in a terrestrial
environment is resolved through endothermy; e.g.
endotherms can live in below-freezing production-
temperature that deactivate the metabolism of
ectotherms
11. Question: why is ectothermy a good strategy in living
in a new environment?
12. Adaptation of animals that
thermoregulate
• Adjusting the rate of heat exchange between the
animal and its surroundings
• e.g. insulation such as feathers, fat
• changes in the circulatory system-
vasodilation/vasoconstriction
• countercurrent heat exchange- arteries are in
opposite direction that of veins in the extremities;
heat exchange is determined by physiology or
environment
13. Cooling through evaporative heat loss
Behavioural response- posture or movement
(migration/hibernation/estivation/winter sleep)
Changing the rate of metabolic heat- applies only to
endotherms
14. Mechanisms of temperature control
Mammals/ birds
Constant heat loss
Constant heat production
Nonshivering thermogenesis vs shivering thermogenesis
18. Amphibians and Birds
Movement is key to heat production
Production of mucus to counter evaporative cooling
Reptiles have scales that inc skin’s SA
Vasoconstriction in extremities of marine iguana
27. Osmoregulation
Functions in maintaining the composition of the
cell’s cytoplasm
Mostly done indirectly
Open circulatory- uses hemolymph
Close circulatory- use interstitial fluid
Kidneys are specialized organs in maintaining the
composition of the body’s fluid composition
28. Transport epithelia
e.g. transport epithelium face the outside
environment to release unwanted solutes but have
tight junction in between cells to inhibit back flow;
functions like the Casparian strip of plants
29. Ammonia
Most common in aquatic animals
Can easily pass through membranes via diffusion
Invertebrates release ammonia all throughout the
body
Fish release ammonia in the form of ammonium ions
through the gills (kidneys excrete only minimal
amount)
Freshwater fishes excrete NH4 ions but also take in
Na ions through the gill epithelium to have a higher
concentration of Na ions compared to the
environment
30. Urea
less toxic compared to ammonia
Need less water in eliminating
Used by mammals, adult amphibians, marine fishes
and turtles
Ammonia+CO2
Transported via the circulatory system and filtered
in the kidneys
31. Can be transported in high concentration due to low
toxicity
Uses more energy
Animal adaptation: amphibians in water excrete
ammonia but excrete urea in land, what is the
advantage of this lifestyle?
32. Uric Acid
relatively nontoxic nitrogenous waste
Insoluble in water and excreted as semisolid paste
Advantage: low water loss
Disadvantage: highly expensive
Present in land snails, insects, birds, reptiles
33. Osmoconformers vs osmoregulators
Osmoconformers- animals that have the same
concentration of body fluid and of the external
environment; live in relatively stable environment
Osmoregulators- maintains the concentration of
body fluid; body fluid is not isoosmotic with that of
the environment
34. Stenohaline- animals that cannot tolerate broad
change in solute concentration
Euryhaline- animals that can tolerate substantial
change in external osmolarity, e.g. salmon