Blue whales (like all baleen whales) are seasonal feeders and carnivores that filter feed tiny crustaceans (krill, copepods, etc.), plankton, and small fish from the water. They are gulpers, filter feeders that alternatively swim then gulp a mouthful of plankton or fish - they lunge into dense groups of small sea organisms (krill or tiny fish) with an open mouth. 50 to 70 throat pleats allow the throat to expand a great deal, forming a gular pouch. The water is then forced through the baleen plates hanging from the upper jaw. The baleen catches the food, acting like a sieve.The blue whale has about 320 pairs of black baleen plates with dark gray bristles in the blue whale's jaws. They are about 39 inches long (1 m), 21 inches wide (53 cm), and weigh 200 pounds (90 kg). The tongue weighs 4 tons (3.8 tonnes).An average-sized blue whale will eat 2,000-9,000 pounds (900-4100 kg) of plankton each day during the summer feeding season in cold, arctic waters ( about 120 days).