Final answer:
Birds and some insects display thoracic endothermy or homeothermy during flight or activity. Birds, including species such as hummingbirds, maintain a constant and elevated body temperature through insulation provided by feathers and a high metabolic rate. Some insects, like the Karner blue butterfly, also maintain a preferred thoracic temperature during flight.
Step-by-step explanation:
Organisms that display thoracic endothermy or homeothermy during flight or activity are primarily birds and some insect species. Birds are endothermic and homeothermic, meaning they maintain a constant and high body temperature that is optimal for their high-energy requirements during flight. For instance, hummingbirds, known for their hovering capabilities, exemplify this trait due to their high metabolic rate necessary for active flight. Their bodies are covered with specialized feathers that serve as both insulations to retain body heat and as a tool for flight.
On the other hand, some insect species, such as the Karner blue butterfly, have a preferred thoracic flight temperature, which is a physiological characteristic reflecting their ability to maintain thoracic endothermy while in flight, despite the rest of the body not maintaining the same temperature. Like birds, this physiological trait allows the muscles used for flight to function optimally.
Both mammals and birds, which are descendants of reptile-like ancestors, have evolved to be endothermic, enabling them to regulate their body temperature internally. This endothermy is in sharp contrast to ectothermic organisms like fish, reptiles, and amphibians that rely on external environmental conditions to regulate their body temperature.