Despite its enormous size -- a full-grown northern right whale (Eubalaena glacialis) weighs almost 50,000 pounds (22,000 kg) -- this slow-moving ocean giant feeds exclusively on tiny crustaceans and other free-floating invertebrates.

Its oral cavity is unlike that of any other mammal: instead of teeth, two curtains of long, narrow baleen plates hang from its arched upper jaw. Baleen, made of the same protein that occurs in hair and fingernails, is indispensable to the right whale's feeding.

Right whales skim-feed by swimming along the surface, mouth open, through swarms of potential prey. Filling its mouth with huge volumes of seawater, it uses its muscular tongue to expel the water sideways through the baleen curtains. As water is driven out, bristly fibers on the inner surface of each plate trap the prey, which the whale then swallows.