The blue whale, the largest animal known to have ever existed on Earth, is known for its immense size and extraordinary mouth. This remarkable feature is central to its survival, enabling a specialized feeding strategy that sustains its massive body. Its mouth is a testament to evolutionary adaptation, designed to efficiently process the vast quantities of food required by such a colossal creature.
Understanding Its Physical Dimensions
Its mouth is of immense scale, reflecting the animal’s overall size. The head, housing this large oral cavity, can be up to 18 feet (5.5 meters) long, though this is less than a quarter of the whale’s body length. The mouth itself can extend approximately 20 feet (6 meters) in length, longer than a typical car. The head’s broad, U-shaped rostrum is adapted for engulfing large volumes of water and prey.
While a blue whale can reach lengths of 98-100 feet (29.9-30.5 meters) and weigh up to 190-199 tons, its head and mouth are dimensioned to maximize feeding efficiency. Its tongue alone can weigh around 2.7 tons, roughly the weight of an elephant.
Specialized Oral Anatomy
The blue whale’s oral anatomy is adapted for filter feeding, featuring baleen plates instead of teeth. These plates, numbering between 260 and 400 on each side of the upper jaw, are made of keratin, the same protein found in human hair and fingernails. Each baleen plate has a frayed, bristly inner edge, forming a sieve that traps small organisms.
Complementing the baleen are expandable throat pleats, also known as ventral grooves. These 60 to 88 accordion-like folds extend from the whale’s chin to its navel. During feeding, these pleats allow the throat to expand, increasing its girth by up to 162% and its length by 38%, accommodating large volumes of water and prey. The lower jaw, consisting of two pieces, can dislocate and pivot apart by almost 90 degrees, further enhancing the mouth’s capacity.
The Lunge Feeding Mechanism
The blue whale’s mouth is central to its unique feeding strategy, known as “lunge feeding.” This technique involves the whale accelerating rapidly towards dense patches of krill, its primary food source. As it reaches the krill swarm, the whale opens its mouth, engulfing prey and a substantial volume of seawater. This engulfment phase lasts approximately five seconds.
The flexible throat pleats expand during this process, allowing the mouth to take in a volume of water that can exceed the whale’s own body volume. After engulfing water and krill, the whale closes its mouth, and its powerful tongue pushes the water out through the baleen plates. The baleen acts as a filter, trapping krill inside the mouth while water is expelled. This process allows blue whales to maximize calorie intake from dense krill patches, abundant during specific seasons.
Enormous Capacity and Daily Intake
The blue whale’s mouth possesses a vast capacity, capable of engulfing large quantities of water and krill in a single gulp. A blue whale can take in up to 220 metric tons (240 short tons) of water at one time. This volume can equal or exceed the whale’s own body mass. During a single bite, a 25-meter blue whale can swallow up to 80,000 liters of water.
To sustain its immense size, a blue whale consumes a large amount of krill daily. An average-sized blue whale needs to consume an estimated 1,120 ± 359 kilograms (2,469 ± 791 pounds) of krill per day. Some studies suggest a blue whale can ingest up to 16 metric tons (32,000 pounds) of krill in a single feeding day, which can represent up to 12% of its own body weight. During peak feeding seasons, a blue whale may perform hundreds of lunges daily to meet its energetic demands.