15. 2 Thermoregulations in ectotherms

thermoregulation

temperature regulation

the temperature of the surrounding is constantly changing and organism have to keep relatively constant body temperature in order for enzymes to function at their optimum rate

ectotherm

cold blooded

How is an animal heated or cooled by the surroundings:

• radiation

• convection

• conduction

• latent heat of evaporation

• exothermic chemical reaction- respiration

• ectotherms mainly rely on behavioural responses

Behavioural responses of ectotherms

• basking in the sun

• orientating their body to maximise radiation from the sun

• lying against warm rock- conductor

• lifting two feet at a time off the ground

• wallowing in mud

• moving into crack and crevices in the rocks where it is shady

Specific examples of behavioural responses to ectotherms

• butterflies spread their wings to increase their SA to absorb enough heat, or they may vibrate their wings to warm their muscles before flying

• Galapagos iguanas contract their muscles and vibrate increasing their metabolism to warm up

Physiological responses of ectotherms

the Namaqua Chameleon

their skin can turn black to absorb the sun’s radiation

their skin can turn white to reflect the sun’s radiation