Why do whales have baleen instead of teeth?

Whales that have baleen, such as the humpback or blue whale, use it to filter-feed on small organisms like krill, plankton, and small fish. Baleen is made of keratin (the same material as human hair and nails) and is arranged in comb-like plates that line the whale’s mouth. When feeding, these whales take in a large mouthful of water, then close their mouths and push the water out, trapping the small prey in the baleen plates. This adaptation allows them to feed efficiently on tiny organisms in the ocean.