bio

Regional endothermy

The strategy of heating not the whole body but only the parts whose speed matters — typically the swimming muscle, the eyes and the brain. Tunas and lamnid sharks arrived at it independently, holding those structures 5–15 °C above the water while the rest of the body sits at sea temperature. The payoff is not top speed — power scales with the cube of speed, so the effect there is mild — but timing: twitch frequency and neural conduction scale directly with metabolic rate, so retained heat buys reaction time. For a pack predator that needs every member to commit inside the same instant, that is the part worth paying for.