Final answer:
Ectotherms rely on external heat to regulate their body temperature, exhibiting behaviors such as basking in the sun or seeking shade to maintain a suitable temperature for survival.
Step-by-step explanation:
Ectotherms, such as fish, amphibians, and reptiles, face challenges in temperature regulation because they rely on external heat sources. Unlike endotherms, ectotherms cannot generate enough metabolic heat to maintain a stable body temperature.
As a result, they exhibit behaviors such as basking in the sun to warm up or seeking shade to cool down. These behavioral adaptations are necessary for them to survive in varying environmental temperatures. For instance, reptiles often bask on rocks to absorb heat, but will also seek cooler areas or water during intense heat to prevent overheating. Additionally, some ectotherms, like bees, use group activity to generate warmth during colder periods.