Temperature control in ectotherms

Question 1

what is a ectotherm?

Answer 1

an organism that relies on external sources of heat to maintain body temperature

Question 2

how are ectotherms different to endotherms?

Answer 2

• not able to control their body temperature as effectively as endotherms
• relies on external sources of heat
• body temperature fluctuates with the external temperature
• some ectotherms can control their body temperature in all and even most extreme conditions

Question 3

what do ectotherms rely on to maintain body temperature?

Answer 3

behavioural responses
but some heat is generated from respiration

Question 4

how do ectotherms increases their body temperature?

Answer 4

• move into a sunny area
• lie on a warm surface
• expose a larger surface area to the sun

Question 5

how do ectotherms decrease their body temperature?

Answer 5

• move out of the sun
• move underground
• reduce the body surface exposed to the sun

Question 6

why do lizards burrow?

Answer 6

hide in burrow at hottest part of the day as it will be cooler as the underground burrow tends to have a more stable temperature but a night it might be warmer than outside

Question 7

how do increase in breathing movements cool a insect down?

Answer 7

when hot rate of breathing and depth of breathing is increased so more water evaporated from the tracheal system which cools the body

Question 7

how do locusts change temperature?

Answer 7

in the early morning they sit side on facing the sun so the can absorb the most heat as more surface is exposed to the sun
midday the sit face on so less surface area is exposed to the sun so absorb less heat
climb to the top of the plant to get away from the soil as it can get hot and radiates heat

Question 8

how does a horned lizard absorb more heat?

Answer 8

can change shape by expanding or contracting its ribcage which increase the surface area exposed to the sun so more heat can be absorbed

Question 9

why do ectotherms turn different colours?

Answer 9

different colours absorb different light wavelengths so can absorb more light and therefore more heat
can reflect light in order to cool down

Question 10

what are the advantages of ectothermy?

Answer 10

less of their food is used in respiration
more of the energy and nutrients gained from food can be converted to growth
they need to find less food
they can survive long periods without food

Question 11

what are the disadvantages of ectothermy?

Answer 11

less active in cooler temperatures, greater risk of predation
may not be capable of activity in winter, seasons dependent
more at risk of climate change