Whales | NOAA Fisheries

Baleen is a filter-feeding system inside the mouths of baleen whales. There are two types of cetaceans: baleen and toothed. Baleen whales, or Mysticetes, have baleen plates which sieve prey, like krill, from the water. Toothed whales, or Odontocetes, have teeth and feed on fish, squid, and other marine mammals such as seals and sea lions.

https://www.fisheries.noaa.gov/whales