Whales, Earth’s largest marine mammals, exhibit remarkable diversity in their forms and diets. Their feeding habits are linked to their biology, behaviors, and environments. Understanding what whales consume provides insight into their ecological roles and how they navigate vast ocean ecosystems. From microscopic organisms to large marine animals, the array of prey whales target highlights their adaptability and the richness of marine life.
Two Main Feeding Groups
Whales are classified into two suborders based on their feeding anatomy: baleen whales (Mysticeti) and toothed whales (Odontoceti). Baleen whales possess baleen plates, comb-like structures made of keratin that hang from their upper jaw. These plates filter small prey from water. Toothed whales have teeth and are active predators, capturing individual prey. This anatomical distinction dictates their feeding strategies and food types.
Diets of Baleen Whales
Baleen whales are filter feeders, straining small organisms from seawater. Their food sources include tiny crustaceans like krill and copepods, small schooling fish such as herring and anchovies, and various forms of plankton. Blue whales, the largest animals on Earth, predominantly feed on krill, consuming up to 16 metric tons daily in the North Pacific. Fin whales also eat krill, copepods, and small schooling fish, while humpback whales prey on krill and small fish.
Different baleen whale species employ distinct filtering techniques. Rorquals (blue, fin, humpback whales) are “gulp feeders.” They engulf large mouthfuls of water and prey, expanding their throat pleats, then use their tongue to force water out through their baleen plates, trapping food. Right whales are “skimmers,” swimming with their mouths open at the surface to continuously filter zooplankton and copepods. Gray whales are unique bottom feeders, rolling on their side to suck in sediment and invertebrates, like amphipods, from the seafloor, filtering them through their coarser baleen.
Diets of Toothed Whales
Toothed whales are active hunters. Their diets are more varied, reflecting their ability to capture individual prey. Their food sources include various species of fish, squid, and octopuses. Larger species, such as orcas, also consume other marine mammals like seals, sea lions, porpoises, and other whales, in addition to fish and cephalopods.
Sperm whales, the largest toothed whales, are renowned for diving deep to hunt giant squid, which form a significant part of their diet. They can consume between 400 and 800 squid per day, though some populations also rely heavily on fish.
Toothed whales use sophisticated hunting strategies, with echolocation as a primary method for locating prey in the dark ocean depths. They emit high-frequency clicks and interpret the returning echoes to pinpoint objects. Orcas, often called “wolves of the sea” due to cooperative hunting, use complex group tactics to capture prey. This can involve creating waves to wash seals off ice floes or working together to herd fish. Some toothed whales, like sperm whales, may generate powerful clicks to stun their prey, giving them an advantage in capture.
Factors Influencing Whale Diets
Several factors influence whale diets beyond their anatomical adaptations. Geographical location plays a significant role, as prey availability varies across ocean regions. Seasonal prey availability is another major determinant, with many whale species migrating to high-latitude feeding grounds during productive summer months to build fat reserves. For instance, humpback whales often switch between krill and schooling fish depending on the ocean’s climate and ecosystem conditions.
Migration patterns are directly tied to these seasonal shifts, as whales travel long distances to reach areas rich in their preferred food. The age and size of a whale can also affect its dietary choices; larger whales typically require more food, and some may shift their diet as they grow. Environmental changes, such as rising ocean temperatures or overfishing, can significantly impact prey distribution and abundance, altering whale diets and affecting their health and migration patterns. Noise pollution from human activities can also interfere with toothed whales’ echolocation abilities, making it harder for them to find food.