Rorqual Lunge Feeding

node · earth · Wherever dense euphausiid patches form

The engulfment manoeuvre that makes the blue whale's size possible and also constrains where it can live. The whale accelerates into a prey patch, opens its jaws and takes in a volume of water comparable to its own mass, then filters it through baleen. Modelling that combined tag kinematics with unsteady hydrodynamics found the energy returned by a single mouthful of dense krill is very large relative to the cost of the lunge - reported as up to about ninety times the energy expended on a dive - but only if the lunge targets extremely high krill densities. Dives in that work lasted between about 3 and 15 minutes with as many as six lunges each. The efficiency is conditional, which is why a blue whale cannot simply feed wherever it happens to be.