The bowhead whale is one of the largest marine mammals, inhabiting the frigid Arctic and subarctic waters. These creatures are adapted to life amidst seasonal sea ice. Reaching lengths of up to 20 meters (62 feet) and weighing over 100 metric tons (200,000 pounds), their size is impressive. Bowhead whales are known for their extraordinary longevity, with some individuals estimated to live for more than 200 years.
Primary Food Sources
Bowhead whales are filter feeders, consuming small marine invertebrates. Their primary prey consists of zooplankton, tiny aquatic organisms that drift within the water column. Copepods and krill are the main components of their diet; copepods are small crustaceans and krill are shrimp-like crustaceans. To sustain their massive body size, a single bowhead whale is estimated to consume about 100 metric tons (over 220,000 pounds) of crustaceans annually. They also ingest other invertebrates and some small fish, though copepods and krill form the bulk of their sustenance.
Unique Filter-Feeding Mechanics
Bowhead whales filter-feed by straining vast volumes of ocean water to capture prey. Instead of teeth, they possess baleen plates, which are comb-like structures made from keratin that hang from their upper jaw. Bowhead whales have the longest baleen plates of any whale species, with individual plates capable of reaching lengths of up to 4 meters (13 feet). Their mouth is disproportionately large, accounting for almost one-third of their entire body length, which facilitates the intake of large water volumes.
The whale feeds by swimming slowly with its mouth agape, allowing water laden with prey to flow inward. As water moves through their mouth, it passes through the fine, hair-like fringes of the baleen plates. This action traps small prey items near the whale’s tongue, while water is expelled outwards. A “cross-flow” filtration mechanism, where water flows largely parallel to the baleen filter, may help prevent smaller prey from tangling in the baleen fringes.
Seasonal Feeding Patterns
Bowhead whales feed intensively during the spring and summer months. These seasons bring an abundance of zooplankton in the nutrient-rich Arctic waters, providing ample food resources. This concentrated feeding allows the whales to accumulate substantial energy reserves in the form of blubber, which can be up to 1.6 feet (50 cm) thick. These thick blubber layers are important for insulation in the cold Arctic environment and provide the energy needed to sustain them through periods of reduced food availability.
Their feeding locations are closely tied to the seasonal movements of sea ice, which influences the distribution and availability of their zooplankton prey. As the sea ice retreats in spring, bowheads migrate northward, following the openings in the ice into productive waters. During winter, they move to areas with more stable ice conditions but still with open water for breathing. The depth of their foraging also shifts seasonally, with shallower dives in spring and summer and deeper dives in fall and winter, corresponding to the vertical migration of lipid-rich zooplankton.