Ectotherms
Ectotherm – an organism that relies on external sources of heat to maintain body temperature
Advantages of Ectothermy
Do not use energy to keep warm therefore:
Less energy is spent on metabolic processes
More energy and nutrients can be used for growth
Require less food to live and can survive long periods without food
Disadvantages of Ectothermy
Less active in cooler temperatures (such as early morning)
At risk from predators while cold
Cannot take advantage of food while cold
Exothermic Temperature Control
To Warm Up To Cool Down
Move to a sunny area or near a heat source Move into shade/out of sun
Lie on a warm surface Move underground
Expose more body surface area to sun Reduce body surface area exposed to sun
Specific Examples
Basking in the sun absorbs heat directly from the sun and the surface they are lying on
Facing side -on to the sun in the morning exposes a larger surface area
Facing head-on to the sun at midday exposes less surface area
Climbing plants at midday to move away from soil since soil radiates heat
Increasing breathing rate and depth of breathing movement causes evaporation from
tracheal system, cooling the body
Expanding ribcage increases surface area exposed to sun
Muscle contractions generate heat through respiration
Body movements open sections of the body for ventilation
Ectotherm – an organism that relies on external sources of heat to maintain body temperature
Advantages of Ectothermy
Do not use energy to keep warm therefore:
Less energy is spent on metabolic processes
More energy and nutrients can be used for growth
Require less food to live and can survive long periods without food
Disadvantages of Ectothermy
Less active in cooler temperatures (such as early morning)
At risk from predators while cold
Cannot take advantage of food while cold
Exothermic Temperature Control
To Warm Up To Cool Down
Move to a sunny area or near a heat source Move into shade/out of sun
Lie on a warm surface Move underground
Expose more body surface area to sun Reduce body surface area exposed to sun
Specific Examples
Basking in the sun absorbs heat directly from the sun and the surface they are lying on
Facing side -on to the sun in the morning exposes a larger surface area
Facing head-on to the sun at midday exposes less surface area
Climbing plants at midday to move away from soil since soil radiates heat
Increasing breathing rate and depth of breathing movement causes evaporation from
tracheal system, cooling the body
Expanding ribcage increases surface area exposed to sun
Muscle contractions generate heat through respiration
Body movements open sections of the body for ventilation
