Humpback whales are marine mammals known for their acrobatic displays. These large creatures, belonging to the baleen whale family, are filter feeders, meaning they have unique feeding habits. Their method of acquiring food involves filtering small organisms directly from the water, a strategy that supports their enormous size and energetic needs.
The Humpback’s Staple Diet
The diet of humpback whales primarily consists of small schooling fish and tiny crustaceans known as krill. These whales are opportunistic feeders, meaning their diet adapts based on the availability of prey in their specific location and during different seasons. While krill is a significant component of their diet, schooling fish often constitute a larger portion in many areas.
Humpbacks consume various species of krill. Their fish prey includes herring, capelin, sand lance, Atlantic mackerel, salmon, anchovies, and sardines. Humpbacks migrate thousands of miles to reach nutrient-rich waters where these prey items are abundant, feeding intensively to build up fat reserves.
Feeding Techniques
Humpback whales employ sophisticated feeding strategies to capture their small, schooling prey. One method is bubble-net feeding, a cooperative hunting technique where groups of whales work together. They blow bubbles in a circular or spiral pattern beneath a school of fish or krill, creating a “net” that traps and concentrates the prey.
After forming the bubble net, the whales lunge upward through the center of the concentrated prey, engulfing large quantities of food. This behavior is learned, not instinctual. Not all humpback whale populations exhibit this behavior.
Another common feeding strategy is lunge feeding, which can be performed solitarily or in groups. During lunge feeding, a whale rapidly opens its mouth and surges through a dense school of fish or krill, taking in enormous volumes of water and prey. This action causes their pleated throat grooves to expand, allowing them to engulf a gulp. Lunge feeding can occur at various depths, from deep underwater to the surface.
The Role of Baleen and Food Consumption
The ability of humpback whales to filter feed is made possible by baleen plates, anatomical structures found in their mouths instead of teeth. These plates are made of keratin, the same protein found in human fingernails and hair, and hang from the whale’s upper jaw. Humpbacks possess between 270 and 400 dark-colored baleen plates, each approximately 30 inches long.
When feeding, the whale opens its mouth to take in a large volume of water and prey. The water is then expelled through the baleen plates, which act like a sieve, trapping the small food items. The whale uses its large tongue to push the water out and scrape the trapped food from the baleen, which is then swallowed. This efficient filtering mechanism allows them to consume vast quantities of tiny organisms.
During their feeding season, humpback whales can consume 1 to 1.5 tons (approximately 2,000 to 3,000 pounds) of food per day. This high volume of consumption is necessary to build up fat reserves needed to sustain them during their long migrations and non-feeding periods, such as breeding seasons. They often feed actively for up to 22 hours a day in their feeding grounds to meet these energy demands.