Describing animals that rely primarily on external heat sources to regulate their body temperature, such as reptiles, amphibians, and fish. Their internal heat production is insufficient to maintain a constant body temperature.
From Greek 'ektos' meaning outside and 'thermos' meaning heat, literally 'outside heat.' The term replaced the older 'cold-blooded' in scientific usage because it more accurately describes the temperature regulation mechanism.
Ectothermic animals can actually be more active and have higher body temperatures than endothermic animals when conditions are right! A lizard basking in the sun can reach 40°C while being incredibly energy-efficient compared to mammals.
Complete word intelligence in one call. Free tier — 50 lookups/day.