thermoregulation in exotics SDL Flashcards
what is a homeotherm
organism that maintains its body temp at a constand level by its metabolic activity
what is a poikilotherm
organism that cannot regulate its body temp except by behavioural means
What are the advantages and disadvantages of homeotherms
Advantages:
- can regulate own body temp
- efficient body use
- more efficient enzyme activity as they function in specific temp range
Disadvantages:
- cannot survive in extreme temps
What are the pros and cons of poikilotherms
Pros:
- dont use energy to maintain temp
- dont need to feed each day as energy is not used in temp regulation
Cons:
- rely heavily on external temp to survive
Why is normal temp of birds and rabbits higher than others?
higher metabolic rate
what is metachromatism
colour change of reptiles
How can metachromatism be used in thermoregulation?
by becoming a darker colour when cold => retain more heat
Becoming lighter => skin reflect light to prevent overheating
What cells in lizard skin enable them to use metachromatism in thermoregulation?
melanophores
Describe the behavioural adaptations used by frogs to prevent freezing in cold weather
seek insulated hiding spots
may bury themselves in mud
Describe the physiological adaptations of frogs to prevent freezing in cold weather
Produce anti-freeze like compounds e.g., glucose, urea which lowers the freezing point of their bodily fluids preventing ice formation within their cells
What strategies do birds use to lose heat in hot weather?
- Extending wings
- elevate scapula feather to expose skin at back of neck
- Shade seeking
- Bathing
Why do birds have poor tolerance for high temps?
no sweat glands
Why do birds rely on behavioural adaptations to stay warm?
no brown adipose fat (used to burn calories to produce heat)
What strategies do birds use to conserve heat in cold weather?
- Fluffing feathers to create insulating layer of air
- Tucking legs and bill into feather to minimise exposed surface area
- Roosting together to share body heat
- Sunbathing
- Shivering
- Reduce metabolic rate
- Find sheltered microhabitats such as tree cavities
- Feather preening (well maintained feather provide better insulation)
Describe the cardiovascular adaptations of birds for thermoregulation
In heat:
- can shunt blood away from left ventricle to legs to aid heat loss
In cold - countercurrent heat exchange in aquatic and wading birds:
- cold blood flowing up from foot cools blood flowing towards foot
- warm blood flowing down to feet warm up cold blood travelling up
- decreases temp gradient between water and arriving blood so heat exchange is slower
