Imagine weighing 145 tons and eating enough to maintain your size, while having no teeth. The baleen species of whales contain some of the most enormous animals on earth, yet they have no teeth. This is the primary difference that sets baleen apart from toothed whales.

Instead of teeth, they have baleen plates comprised of keratin. This is the same substance that human nails and hair are made of. Baleen consists of hundreds of long, rough bristles that hang from their upper jaws. The edges are made of fibrous keratin strands that form a filter. A baleen whale-s diet contains krill, plankton and small fish, which get sifted out of the water or sand by their baleen. These huge mammals can filter out, and take in tons of food a day.

Besides being larger and having no teeth, baleen whales differ from toothed whales in other ways. Baleen whales tend to move more slowly, and have smaller dorsal fins. They also have two blowhole openings, instead of just one.

The blue whale is a species of baleen, and is the biggest animal to inhabit the planet. They might be the giants of the oceans, but they feed on some of the tiniest creatures in the world. No teeth required.