In baleen whales, what comb-like structures filter food from seawater?

In baleen whales, comb-like baleen plates filter food from seawater.

Baleen is made of keratin, the same tough structural protein found in human fingernails and hair. Plates hang from the upper jaw in rows, with hairy fringes that form a filtering curtain. A whale takes in a large mouthful of seawater, then pushes the water out through the baleen while retaining krill, small fish, or other prey.

Different whales use this apparatus in different ways. Humpback whales may herd prey with bubble nets, right whales skim slowly through plankton-rich water, and blue whales lunge through dense krill patches. Baleen whales have no functional teeth as adults, unlike toothed whales such as sperm whales and dolphins. Baleen grows continuously and is gradually worn at its fringes, so the plates must remain strong while staying flexible.