Whales are carnivores, though their feeding methods differ from many other meat-eating animals. While some whales possess teeth, baleen whales have evolved a unique approach to acquiring food. Their specialized system filters tiny organisms from the water, establishing them as carnivores with an unconventional twist.
What Defines a Carnivore
A carnivore obtains its food and energy by eating other animals. This dietary classification distinguishes them from herbivores, which consume plants, and omnivores, which eat both plants and animals. Many carnivores possess adaptations such as sharp teeth and specialized digestive systems suited for processing animal matter. Their primary reliance is on animal protein for sustenance.
Baleen Whales: Built for Filter Feeding
Baleen whales (suborder Mysticeti) have a highly specialized feeding system using baleen plates instead of teeth. These plates, made from keratin—the same protein found in human fingernails and hair—hang from the upper jaw, acting like a sieve. Their number and length vary by species. The inner edge of each plate has fine, hairy fringes that interlock, forming a fibrous mat to trap prey as water flows through.
Gulp feeders, like blue whales and humpback whales (also known as rorquals), have distinctive throat pleats. These expandable pleats allow them to engulf enormous volumes of water and prey. After taking in water, they contract throat muscles and use their tongue to push water out through the baleen plates, trapping food inside.
In contrast, skim feeders, like right whales and bowhead whales, swim with mouths continuously open through dense prey patches. As they move, water flows into their mouths and filters out through the baleen, catching tiny organisms in the bristly fringes. Gray whales represent a unique third style, bottom feeding, where they plow through seafloor sediments to filter invertebrates. Each feeding style is intricately linked to the whale’s anatomy, including the specific characteristics of their baleen plates, skull shape, and jaw size.
The Diet of Baleen Whales
Despite their enormous size, baleen whales primarily consume small organisms. Their main food sources include krill (small, shrimp-like crustaceans), copepods (another type of small crustacean), and small schooling fish like anchovies and sardines. Different species of baleen whales specialize in different prey; for example, blue whales feed almost exclusively on krill, while right whales often target smaller zooplankton like copepods. Humpback whales consume both krill and small schooling fish, and gray whales filter invertebrates from bottom sediments.
Baleen whales consume vast quantities of these small animals to sustain their massive bodies. A single blue whale can ingest an average of 16 metric tons of krill in a day during its feeding season. Recent studies suggest that baleen whales may eat up to three times more prey than previously estimated, with daily consumption ranging from 5% to 30% of their body mass. For a blue whale, this can mean consuming approximately 8,000 pounds of krill daily for about 120 days of the year. This immense intake of animal-based food, filtered from the ocean water, classifies baleen whales as carnivores, despite their unique filter-feeding adaptation.