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How do baleen whales filter krill from seawater?

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Two wild horses graze on tall grass in the open prairie of Theodore Roosevelt National Park, with rolling badlands visible in the background. — Feeding behaviour Wild horses graze in the Badlands of North Dakota.

Baleen whales are specialized filter feeders that obtain krill and other small organisms by straining them from seawater using a unique apparatus in their mouths.12

The process functions as follows:

Engulfment: The whale opens its mouth to take in enormous quantities of water containing concentrations of prey.3
Filtration: The whale’s mouth contains baleen—long, comb-like plates made of keratin that hang in two transverse rows from the roof of the mouth.13
Straining: When the whale closes its mouth, it squeezes the water out through the sides. The inner edges of the baleen plates are frayed into bristles, which act as a sieve to trap the tiny prey while allowing the water to flow back out.132

This efficient feeding mechanism allows these large marine mammals to consume significant amounts of food in a single mouthful.1