5.1.1 Thermoregulation In Ectotherms Flashcards
What is Thermoregulation
The maintenance of a relatively constant core temperature
What things affect how an organism heats up or cools down as a result of their surroundings
- Endothermic chemical reactions
- Latent heat of evaporation: objects cool as they evaporate from surface
- radiation: transmission of electromagnetic waves to and from the air, water or ground
- convection: heating and cooling by currents in the air or water
- conduction: heating as a result of the collision of molecules. Ground and water are good conductors of heat
What are ectotherms
Most animals are ectotherms and use their surroundings to warm their bodies. Their core body temp is heavily reliant on the environment. This includes all invertebrates, fish, amphibians and reptiles.
Many ectotherms living in water however don’t need to Thermoregulation as water hella stable sl temp does not change much. However ectotherms living on land do need to Thermoregulate a lot more. Temperature can change dramatically between seasons and even over a 24hr period so ectotherms develop a range of strategies to help them warm or cool
What are endotherms
All mammals and birds are endotherms. They rely on their metabolic processes to warm them up and usually maintain a relatively stable core temp all year and all day round regardless of external temp. They have adaptations that allows them to maintain their internal body temp to take advantage of the warmth from the environment. As a result, endotherms can survive in hella conditions. Metabolic rate of endotherms is like 5x more higher than ectotherms so they require more energy.
Behavioural responses of ectotherms in thermoregulation to increase tmwp
Some may bask in the sun in order to heat up and stimulates their metabolism to the correct speed. For sample lizards often bask for long periods in order be warm enough to move fast and hunt their prey like insects or locus.
Increase body temp by conduction - pressing their bodies against the warm ground. And by exothermic metabolic reactions. Galápagos iguanas will rapidly vibrate or contract their muscles to raise their body temp.
Behavioural responses of endotherms to reduce temp
Shelter from the sun by seeking shade by hiding in cracks in rocks, or digging burrows.
They also press their bodies against cool surfaces like earth or stones, or simply just move to available mud or water.
They orient their bodies so the least surface area is exposed to sun
Physiological responses to warming 
Most thermoregulation is a result on behavioural changes but there are some physiological ones too.
Dark colours absorb more radiation than light colours do. Lizards in colder climates tend to have darker colours than lizards in hotter climates. Some lizards can also alter their heart rate to increase or decrease the metabolic rate and sometimes affect cooling
Where can ectotherms survive when endotherms cannot
Use less energy to regulate temperatures so they can survive in very difficult habitats where food may be scarce
