15.2 thermoregulation in ectotherms

what is thermoregulation

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

changes the affect the bodily temperature of an organism

• exothermic chemical reactions

• latent heat of evaporation - objects cool down as water evaporates from a surface

• radiation - the transmission of electromagnetic waves to and from the air, water, or ground

• convection - the heating and cooling by currents of air or water

• conduction - heating as a result of the collision of molecules

what are ectotherms

• they use their surroundings to warm their bodies - their core temperature is heavily dependant on their environment

• many ectotherms live in water and do not need to thermoregulate due to the high specific heat capacity of water

endotherms

• eg. mammals and birds

• rely on their metabolic processes to warm up and they usually maintain a very stable core body temperature regardless of the outside temperature

• they have a high metabolic rate

• they can survive in a wide range of environments

behavioural responses to regulate body temperature

• basking in the sun so the maximum surface area is exposed to the sun

• insects spread their wings to increase the available surface area exposed to the sun to get warm enough to fly

• increase their body temperature through conduction by pressing their bodies against the ground

• contracting their muscles and vibrating to increase cellular metabolism to increase their body temperature

• to cool down they can seek shade or hide in rocks or dig burrows

physiological responses to regulate body temperature

• lizards living in colder climates tend to be a darker colour

• ectotherms alter their heart rate to increase or decrease the metabolic rate