Power and speed of swimming dolphins

The belief that dolphins have an extraordinary ability to generate propulsive power or can modify the water flow over their bodies to the low-resistance laminar flow is pervasive in the perception of the animals by the public and by some of the biology communities. I analyzed measured swimming speeds for dolphins of the Stenella-Delphinus morphology. A conservative hydrodynamics model equivalent to 119% of the drag of a rigid fusiform body (the added 19% compensates for the drag induced by propulsion) and a metabolic rate of 13.4 times the projected resting metabolic rate are consistent with measured maximum steady-state speeds. Measured routine swimming speeds are also consistent with this same hydrodynamics model and with metabolic rates for routine activity of other swimming and terrestrial homeotherms. Energy expenditure for swimming dolphins is entirely within expected ranges and no extraordinary mechanisms are necessary to explain observations.