Baleen plate or frond. Baleen comes from whales that do not have teeth, but instead have rows of baleen plates in the upper jaw - flat flexible plates with frayed edges, arranged in two rows, looking like combs of thick hair. Baleen is composed of keratin, the same substance as hair, horn, claws and nails. Whales swim along opening their huge mouths and letting in gallons of water and their food, which includes krill and other types of plankton and also small schooling fish. This is called filter feeding. Whales are the only vertebrate group to use this method of feeding in great abundance, and it has allowed them to grow to immense sizes. The blue whale, the largest animal alive and probably the largest animal to ever have lived, is a baleen whale. Some baleen whales in Alaska are the bowhead, humpback, gray, minke, fin, and blue whale. 30"L x 2"W.