How do blue whales eat?

Quick Answer

Blue whales eat through a highly specialized technique called lunge feeding. They accelerate toward dense clouds of krill, open their enormous mouths, and engulf huge quantities of water and prey in a single gulp. Rows of bristle-like baleen plates then filter the water out while trapping the tiny crustaceans inside. During peak feeding season, a single blue whale can consume up to 6 tons (12,000 pounds) of krill per day using this method. Despite being the largest animal ever to live on Earth, the blue whale’s entire diet depends on one of the ocean’s smallest creatures.

What You Need to Know

Lunge Feeding: A High-Energy Strategy

Blue whales are rorqual whales, a group within the baleen whale family distinguished by the pleated grooves running along their throat and chest. These grooves are central to how they eat. When a blue whale identifies a dense swarm of krill—often using echolocation cues and visual scanning—it begins its feeding lunge.

The whale accelerates to roughly 6–8 miles per hour, then drops its lower jaw open to nearly 90 degrees. As the mouth opens, the ventral grooves (numbering between 55 and 88) expand like an accordion, allowing the throat pouch to balloon outward. In a single lunge, a blue whale can take in up to 110,000 pounds of water and krill—a volume larger than the whale’s own body.

This process generates enormous drag and requires a tremendous amount of energy. Research has shown that lunge feeding is one of the most energy-intensive feeding strategies in the animal kingdom. Blue whales only profit from it because krill occur in extremely dense aggregations, making each lunge worth the effort.

Baleen Plates: Nature’s Filter System

Instead of teeth, blue whales possess baleen plates—flat, flexible structures made of keratin (the same protein found in human fingernails). A blue whale has between 260 and 400 plates hanging from each side of its upper jaw, and each plate is fringed with coarse, hair-like bristles along its inner edge.

After engulfing a mouthful of krill-laden water, the whale pushes its massive tongue forward against the baleen, forcing seawater out through the bristled edges. The krill—each only 1–2 centimeters long—are too large to pass through the baleen fringe and remain trapped inside the mouth. The whale then swallows the concentrated mass of krill whole. Its throat, despite being attached to such a colossal body, is only about the diameter of a small beach ball, which is why blue whales feed exclusively on tiny prey. For more on this surprising fact, see our page on whether whales can swallow humans.

Where and When Blue Whales Feed

Blue whales are not constant feeders. Their annual cycle revolves around dramatic seasonal migrations between cold, nutrient-rich feeding grounds at high latitudes and warmer, low-latitude breeding grounds. They do the vast majority of their eating during summer months in polar and subpolar waters, where upwelling currents create massive blooms of Antarctic krill (Euphausia superba) in the Southern Hemisphere or North Pacific krill (Euphausia pacifica and Thysanoessa spinifera) in the Northern Hemisphere.

During feeding season, a blue whale may perform lunge-feeding dives repeatedly throughout the day. A typical foraging dive lasts about 10 minutes and reaches depths of roughly 100–300 meters, where krill tend to form their densest swarms. The whale may execute several lunges per dive before returning to the surface to breathe. To learn more about blue whale diving capacity, see how long can whales hold their breath.

When krill density drops below a profitable threshold, blue whales stop feeding and rely on their enormous blubber reserves to sustain them during migration and the breeding season. This feast-or-famine strategy means that changes in krill abundance—driven by ocean warming and sea-ice loss—pose a direct threat to blue whale survival. The species is currently listed as Endangered on the IUCN Red List, and scientists closely monitor krill populations as a key indicator of blue whale habitat health. You can learn more about their population status at how many blue whales are there.

Scale of Consumption

To fuel a body that can stretch up to 100 feet long and weigh as much as 150,000 kilograms, blue whales must eat staggering amounts. The widely cited figure of 6 tons of krill per day comes from peak feeding periods. Over an entire feeding season of roughly four to six months, a single blue whale may consume over 1,000 tons of krill. Recent research published by Stanford University and NOAA suggests that some historical estimates may even have undervalued the true intake, with tagged whales showing higher lunge rates than previously assumed. For a sense of the body size that demands this level of fuel, see how big is a blue whale.

Key Takeaways

• Lunge feeding is the blue whale’s primary feeding method: a high-speed, open-mouthed charge into dense krill swarms that captures up to 110,000 pounds of water and prey per gulp.
• Baleen plates (260–400 per side) act as a natural filtration system, straining krill from seawater before the whale swallows.
• Blue whales feed almost exclusively on krill, consuming up to 6 tons per day during peak season despite having a relatively small throat.
• Feeding is seasonal and location-dependent—blue whales gorge in cold, productive waters during summer and fast during winter migration to breeding grounds.
• Because their survival hinges on krill availability, climate-driven changes in ocean temperature and sea-ice extent are among the most significant conservation threats facing blue whales today.
• To explore what other whale species eat, visit what do whales eat.