Passage I

Fin whales engulf and filter massive amounts of water and prey during an event called lunge feeding. The 5 distinct stages of a lunge-feeding event are listed and described below.

·Stage 1: Rapid acceleration of the whale

·Stage 2: Mouth opening and engulfment

·Stage 3: Onset of mouth closure

·Stage 4: Continued mouth closure and pre-purging

·Stage 5: Purging (filtering water from prey)

The figure below shows how a fin whale's speed and gape angle (angle between the top and the bottom of the fin whale's mouth) varied during a lunge-feeding event.

Figure adapted from J.Potvin et al., “Passive Versus Active Engulfment: Verdict from Trajectory Simulations of Lunge-Feeding Fin Whales Balaenoptera physalus."©2009 by The Royal Society.