Hydrodynamic & Bioenergetic Tradeoff
Rorqual whales execute the largest biomechanical action in the animal kingdom. Opening their mouth at high speeds causes massive fluid drag ($F_{drag} = \frac{1}{2} \rho v^2 C_d A$), rapidly decelerating the whale while expanding its ventral groove blubber pouch to hold more water than its own body mass.
Net Energy = Gross Krill Harvest (MJ) - [Drag Work + Mass Acceleration Cost (MJ)]
After engulfment, the whale uses tongue muscle pressure to force water out through baleen plates, retaining hundreds of kilograms of krill inside the mouth cavity.