ectothermia

Ectothermy is a form of thermoregulation in which an organism derives its metabolic heat primarily from external sources. This contrasts with endothermy, where the organism generates heat internally through metabolic processes. Ectothermic animals, commonly referred to as "cold-blooded," rely on their environment to regulate their body temperature.

Behavioral thermoregulation is a key strategy for ectotherms. They may bask in the sun to absorb heat, seek shade to cool down, or move between different microhabitats with varying temperatures. For example, reptiles often bask on rocks in the morning to warm up their muscles before becoming active. Amphibians may immerse themselves in water or burrow underground to avoid extreme temperatures.

The body temperature of ectotherms fluctuates with the ambient temperature, meaning their physiological processes, such as digestion, movement, and immune function, are directly influenced by external conditions. This can limit their activity in colder environments or at night. However, ectothermy is generally more energy-efficient than endothermy, requiring less food intake to maintain body temperature. This allows ectotherms to thrive in environments where food resources are scarce. Many fish, amphibians, reptiles, and invertebrates are ectothermic.