The fin whale is a sleek and fast marine inhabitant, often called the “greyhound of the sea.” As a baleen whale, it consumes vast quantities of small marine organisms.
Primary Food Sources
Fin whales primarily consume small, schooling organisms, with their diet largely depending on regional and seasonal availability. Krill, which are small crustaceans, constitute a significant portion of their diet, particularly in cold, nutrient-rich polar and subpolar waters.
Small schooling fish also form a substantial part of their diet, especially in temperate regions. Common fish prey include herring, capelin, sand lance, and cod. Fin whales have been observed to consume anchovies, sprat, and mackerel as well. While less common than krill or fish, squid can occasionally be a minor component of their diet.
Feeding Strategy
Fin whales employ an efficient filter-feeding method to gather their food. They utilize a technique called lunge feeding, where they accelerate and open their mouths to engulf large volumes of water and prey simultaneously. Their throat features 50 to 100 expandable pleats, allowing their mouth cavity to balloon outwards and take in up to 70 cubic meters of water in a single gulp.
After engulfing the water and prey, the whale closes its mouth and expels the water through specialized structures called baleen plates. These plates, made of keratin (similar to human fingernails), hang from the upper jaw and act as a sieve, trapping the small prey inside while the water is pushed out. An adult fin whale possesses between 260 and 480 baleen plates on each side of its mouth, which can measure up to 76 centimeters in length.
Dietary Adaptations and Seasonal Feeding
Fin whales undertake extensive seasonal migrations that influence their dietary patterns. They typically travel from warmer, low-latitude breeding grounds during winter to colder, high-latitude feeding grounds in summer, where food is abundant.
For example, a decrease in the abundance of certain krill species due to environmental changes can lead fin whales to broaden their diet to include more fish. To sustain their massive bodies and high metabolic rate, fin whales consume an immense quantity of food, up to 2 tons (1,800 to 2,000 kilograms) of prey per day during feeding seasons. As major consumers, fin whales play a role in marine ecosystems by processing large amounts of biomass and contributing to nutrient cycling.