The largest feeding event
A whale eats many thousands of individual krill with each gulp.
Its meals are the largest single feeding events on Earth.
A whale approaches concentrations of krill and quickly lunges forward, twisting its body as it opens its mouth to capture the mass of tiny crustaceans.
Having expanded the throat pouch to catch as much food as possible, the whale closes its mouth and pushes the excess water out through the baleen by expanding its tongue, leaving the krill trapped in the baleen filters.
Scientists now know that this fast, dynamic movement requires huge amounts of energy.
Every time it spots potential prey, the whale must decide whether the nutrition gained from the krill will be large enough to be worth spending energy on.
If the animal makes the right decision, the rewards can be enormous. A blue whale can engulf tonnes of krill in one mouthful, taking in more than 100 times the energy needed to lunge.
A photo of whale feeding, 2017 © Oregon State University / A diagram of a blue whale feeding © 2017 Kylie Duthie / Northern krill © Øystein Paulsen, GNU Free Documentation License