Of the three baleen whale families, the Right Whales are the Skimmers. These whales have very long baleen (over 4 meters/13 feet) and a mouth that looks like it is curved upside down. The long baleen and the upward curve of the lower jaw allow these whales to swim around slowly with their mouths partially open. The lower jaw will support the bottom of the long baleen plates, which would otherwise bend uncontrollably. This skimming behavior causes the water to move in through the front of the mouth and out through the baleen. Therefore, the food gets stuck on the inside of the baleen and the whale just has to close its mouth intermittently and lick it off. These slow-swimming whales have very fine baleen and feed on very small food items, such as krill (2-5 cm/1-2 inches long) and nearly microscopic copepods.

The Rorquals are the Gulpers. These whales have relatively short baleen (up to 90 cm/3 feet). They are sleek, fast swimmers capable of bursts of speed up to 35 km/hr. They lunge through concentrated patches of prey and suddenly open their jaws wide, up to an angle of over 100°. This causes a large pouch on their throat to fill up with water and prey, very much like that of a pelican's pouch. When a blue whale has its pouch completely filled, it is large enough to hold a small truck. The whale then closes its mouth almost completely, so that the water in the pouch has to pass through the baleen on the way out. Thus, the prey is caught in the baleen and swallowed after all the water has been ejected. The prey items vary with location for the rorquals. All rorquals found in the Southern Ocean, around Antarctica (all species except the Bryde's whale) feed on krill. In other parts of the world they feed on a variety of prey. The larger whale species tend to feed on smaller prey, farther down the food web, while the smaller whale species tend to feed on larger prey, farther up the food chain. The blue whale is a krill specialist, while the other whale species also eat schooling fish and, in some cases squid.

The Gray Whale is the Bottom Feeder, or "mud sucker". The head and mouth of this whale is short and stout, with course and relatively short (up to 25 cm/10 inches) baleen. The whale will roll over on its side and suck up a mouthful of bottom sediment, including animals that live in, on and just above the bottom. It will then mostly close its mouth and use its tongue to liquefy the sediment and filter it out through the baleen. The course baleen is thought to be an adaptation to the excessive wear and tear of filtering mud and other sediments. Gray whales mostly feed on amphipods, small bottom-dwelling crustaceans.