15.2 Thermoregulation in ectotherms

Question 1

What is thermoregulation?

Answer 1

Maintenance of a relatively constant core body temperature to maintain optimum enzyme activity

Question 2

What physical processes do the temperature fluctuations of an organism depend on?

Answer 2

Exothermic chemical reactions

Latent heat of evaporation

Radiation

Convection

Conduction

Question 3

What does the ‘latent heat of evaporation mean’?

Answer 3

Objects cool down as water evaporates from a surface

Question 4

What is ‘radiation’?

Answer 4

The transmission of electromagnetic waves to and from air, water or ground

Question 5

What is ‘convection’?

Answer 5

Heating and cooling by currents of air or water

Warm air / water rises and cooler air / water sinks
-> convection currents set up around organism

Question 6

What is ‘conduction’?

Answer 6

Heating as a result of the collision of molecules

Ground and water are good conductors of heat

Question 7

What are ectotherms?

Answer 7

Animals that use their surroundings to warm their bodies

‘Outside heat’

Question 8

What are examples of ectotherms?

Answer 8

Invertebrate animals, fish, amphibians and reptiles

Question 9

Why do ectotherms living in the water not need to thermoregulate?

Answer 9

High heat capacity of water means the environment’s temperature does not change much

Question 10

What are endotherms?

Answer 10

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’

Question 11

How much higher is the metabolic rate of endotherms compared to ectotherms?

Answer 11

5 times higher

Question 12

What do the behavioural responses of ectotherms allow them to gain or reduce?

Answer 12

Radiation they absorb from the Sun

Question 13

What are some behavioural responses of ectotherms to warm up USING THE SUN?

Answer 13

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

Question 14

What are some behavioural responses of ectotherms to warm up by NOT using the Sun?

Answer 14

Conduction; pressing their bodies against the warm ground

Exothermic metabolic reactions (cannot actually CHOOSE to do this)

Question 15

Why do ectotherms cool down?

Answer 15

To prevent their core temperature from reaching a certain point and enzymes begin to denature

Question 16

What are some behavioural responses of ectotherms to cool down?

𝗦𝗠𝗢𝗖𝗦𝗕𝗣𝗠

Answer 16

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

Question 17

What are examples of ectotherms and how do they warm up?

𝗟𝗜𝗠𝗕

Answer 17

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

Question 18

What are some physiological responses of ectotherms to warming?

Answer 18

Cold climates -> dark colours

Alter heart rate -> alter metabolic rate

Question 19

Why do ectotherms need less food than endotherms?

Answer 19

They spend less energy regulating their temperatures

Question 20

Why are lizards living in cold climates darker than those in hotter climates?

Answer 20

Dark colours absorb more radiation than light colours

Question 21

How is the temperature of a lizard when it is in lab conditions with no shelter?

Answer 21

Temperature of lizard is practically the same as environment’s