The posterior border of the nasals and premaxillae lie anterior to the supraorbital processes of the frontals. The rostrum is high, narrow, and arched. Baleen plates are long and narrow, and they number more than 350 on each side of the upper jaw. The right and left baleen rows are separated in the front of the mouth. Right whales feed largely on copepods, which they catch by swimming slowly, with their mouths open, through concentrations of these crustaceans.
Water flows into the huge mouth and out between the baleen plates.
Food is trapped on the fringes of the plates and scraped off with the tongue. They normally feed at or near the surface. These whales live singly or in small groups of up to 3 or 4 individuals. Their stocks were severely depleted by whaling, and they remain low. Walker's Mammals of the World, 4th edition .