Final answer:
Ectotherms living in water do not need to thermoregulate because their body temperature is regulated by the water temperature.
Step-by-step explanation:
Ectotherms living in water do not need to thermoregulate because their body temperature is regulated by the water temperature. They are able to absorb heat from the surrounding water or release heat into it, depending on the temperature gradient. This allows them to maintain a stable body temperature without the need for internal mechanisms of thermoregulation.
For example, fish are ectotherms that live in water. Their body temperature matches the temperature of the water they inhabit. They can adjust their level of activity and move to different water depths to find the temperature range that suits them best.
Additionally, the water provides a more stable thermal environment compared to air. Water has a higher heat capacity, which means it can absorb and retain heat more effectively. This allows aquatic ectotherms to avoid drastic changes in temperature and maintain relatively stable body temperatures.