15.2 Thermoregulation in ectotherms Flashcards
What is thermoregulation?
Maintenance of a relatively constant core body temperature to maintain optimum enzyme activity
What physical processes do the temperature fluctuations of an organism depend on?
Exothermic chemical reactions
Latent heat of evaporation
Radiation
Convection
Conduction
What does the ‘latent heat of evaporation mean’?
Objects cool down as water evaporates from a surface
What is ‘radiation’?
The transmission of electromagnetic waves to and from air, water or ground
What is ‘convection’?
Heating and cooling by currents of air or water
Warm air / water rises and cooler air / water sinks
-> convection currents set up around organism
What is ‘conduction’?
Heating as a result of the collision of molecules
Ground and water are good conductors of heat
What are ectotherms?
Animals that use their surroundings to warm their bodies
‘Outside heat’
What are examples of ectotherms?
Invertebrate animals, fish, amphibians and reptiles
Why do ectotherms living in the water not need to thermoregulate?
High heat capacity of water means the environment’s temperature does not change much
What are endotherms?
Animals that rely on their metabolic processes t warm up and usually maintain a very stable core temperature (regardless of their environment’s temperature)
‘Inside heat’
How much higher is the metabolic rate of endotherms compared to ectotherms?
5 times higher
What do the behavioural responses of ectotherms allow them to gain or reduce?
Radiation they absorb from the Sun
What are some behavioural responses of ectotherms to warm up USING THE SUN?
Bask in the Sun
Orientate their bodies so that the maximum surface area is exposed to the Sun
Extend areas of their body to increase the surface area
What are some behavioural responses of ectotherms to warm up by NOT using the Sun?
Conduction; pressing their bodies against the warm ground
Exothermic metabolic reactions (cannot actually CHOOSE to do this)
Why do ectotherms cool down?
To prevent their core temperature from reaching a certain point and enzymes begin to denature
What are some behavioural responses of ectotherms to cool down?
𝗦𝗠𝗢𝗖𝗦𝗕𝗣𝗠
𝗦helter from the Sun
𝗠inimise movements to reduce metabolic heat generated
𝗢rientate bodies so less surface area exposed to Sun
Hiding in 𝗖racks in rocks
Seek 𝗦hade
Dig 𝗕urrows
𝗣ress their bodies against cool, shady earth
Move into available water or 𝗠ud
What are examples of ectotherms and how do they warm up?
𝗟𝗜𝗠𝗕
𝗟izards bask for long periods to get warm enough to move fast and hunt their prey
Galapagos 𝗜guanas contract muscles and vibrate to increase cellular metabolism -> raise body temperature
𝗠oths vibrate wings before flight to warm up
𝗕utterflies orientate and spread their wings to warm up for flying
What are some physiological responses of ectotherms to warming?
Cold climates -> dark colours
Alter heart rate -> alter metabolic rate
Why do ectotherms need less food than endotherms?
They spend less energy regulating their temperatures
Why are lizards living in cold climates darker than those in hotter climates?
Dark colours absorb more radiation than light colours
How is the temperature of a lizard when it is in lab conditions with no shelter?
Temperature of lizard is practically the same as environment’s
