Baleen or whalebone is the means by which baleen whales feed. These whales don't have teeth, but instead have rows of baleen plates in the upper jaw – flat, flexible plates with frayed edges, arranged in two parallel rows, looking like combs of thick hair. Baleen isn't bone, but is composed of keratin, the same substance as hair, horn, claws and nails. Whales use these combs for filter feeding. Whales are the only vertebrate group to use this method of feeding in great abundance (flamingo… (More on Whalebone)