What Do Whales Eat?

Short answer

• Whales are carnivores, but there is no single whale diet. The answer depends first on which of the two great groups a whale belongs to. Baleen whales have plates of baleen instead of teeth, and they filter small prey from seawater. Their food is mostly krill, copepods, and small schooling fish. Toothed whales have teeth and hunt prey one item at a time, or in coordinated groups. Their food is mostly fish and squid, and for some populations it also includes seals, other whales, sharks, and seabirds. That split explains the most surprising fact about whale diets. Some of the largest animals on Earth eat some of the smallest animals in the ocean. A blue whale, the largest animal known to have lived on Earth, feeds almost exclusively on krill, which are tiny shrimp-like animals. NOAA Fisheries states that some of the biggest blue whales may eat up to 6 tons of krill a day. At the other end of the scale, a sperm whale, the largest toothed whale, dives deep to hunt squid, sharks, skates, and fish, and NOAA Fisheries states that it can consume about 3 to 3.5 percent of its body weight per day. Diet also changes with species, place, and season. A humpback whale in a cold feeding ground may take krill and small fish in summer and then fast for much of the winter breeding season, living on blubber built up during feeding. A gray whale on a northern feeding ground may scoop amphipods from the seafloor, while a right whale in another ocean may skim copepods from surface water. A killer whale population that eats mainly salmon cannot be treated as if it eats the same food as a killer whale population that eats mainly seals. The species name alone does not tell you what is on the menu. The population, the place, and the season do.

The two groups that decide the menu

Whales, dolphins, and porpoises together form the group called cetaceans. Within that group, the feeding divide is simple to state. Baleen whales, also called mysticetes, have baleen plates hanging from the roof of the mouth. Toothed whales, also called odontocetes, have teeth. Whale and Dolphin Conservation explains that baleen whales extract prey as seawater flows through, or is forced through, their baleen plates, while toothed whales use teeth to grab and hold prey and use echolocation, which is sound based navigation and hunting, to find and target prey.

Baleen is made of keratin, the same protein that forms human fingernails and hair. Hundreds of overlapping plates hang down like curtains, and the number, size, and color of the plates differ by species. Water passes out through the baleen, and prey stays inside, where the tongue can move it back to be swallowed. A whale does not chew krill. It strains it, collects it, and swallows it.

Toothed whales work in the opposite way. They detect, chase, grab, and swallow individual prey, often whole or in large pieces, rather than chewing it into small bites. Their teeth grip and, in some species, tear, but do not grind food the way human molars grind. That is why a toothed whale with only a few visible teeth, such as some beaked whales, can still be an effective squid hunter.

| Group | Mouthparts | Main prey | Typical feeding style | | Baleen whales | Baleen plates, no teeth | Krill, copepods, small schooling fish, and, for gray whales, seafloor invertebrates such as amphipods | Filter feeding: lunge feeding, skim feeding, or bottom feeding | | Toothed whales | Teeth | Fish, squid, octopus, and, in some populations, seals, other whales, sharks, and seabirds | Active hunting: echolocation, chasing, suction feeding, and cooperative hunting |

Baleen whales: small prey, huge mouthfuls

Blue whales and the krill specialists

Blue whales keep the story simple, and that simplicity is part of their vulnerability. NOAA Fisheries states that blue whales feed almost exclusively on krill, straining huge volumes of ocean water through their baleen plates. The same source states that the primary diet of blue whales is krill, although fish and copepods may occasionally be part of the diet. When a blue whale hunts, it swims toward a large school of krill with its mouth open, closes its mouth around the krill while inflating its throat pleats, and then pushes the trapped water out with its tongue while the baleen keeps the krill inside.

That method only pays off when krill are dense. A blue whale cannot profitably chase scattered single krill across empty water. It needs patches, which move with currents, seasons, and ocean conditions. NOAA Fisheries notes that blue whale distribution is driven largely by food availability, and that the whales occur in waters where krill are concentrated. This is a useful rule for the whole baleen group: follow the prey patch, not the map.

Daily totals should be read as estimates for a feeding whale in a rich patch, not as a fixed ration for every day. A blue whale that is migrating, breeding, or nursing a calf in warm water is not feeding at the same rate. Other tag based studies have given larger figures for some populations, because they count lunges, mouth volume, and prey density in a different way.

Fin whales: krill plus fish plus squid

Fin whales show how a baleen whale can stay a filter feeder and still broaden the menu. NOAA Fisheries states that during the summer, fin whales feed on krill, small schooling fish including herring, capelin, and sand lance, and squid, by lunging into schools of prey with the mouth open. The whale uses 50 to 100 accordion-like throat pleats to gulp large amounts of food and water, and then filters the food from the water using baleen plates. NOAA Fisheries also states that a fin whale eats up to 2 tons of food daily, and that fin whales fast in the winter while they migrate to warmer waters.

That winter fast is a key part of the baleen story: feeding is seasonal work, and blubber is stored energy. A fin whale that feeds hard in summer is building the fat layer that will carry it through migration and breeding, when food is scarce. The same pattern, in different proportions, runs through humpback, gray, right, and bowhead whales.

Humpback whales: generalists with tricks

Humpback whales are the most flexible of the large baleen whales, and the most inventive in how they catch food. NOAA Fisheries states that humpback whales filter feed on small crustaceans, mostly krill, and small fish. It also states that during the warmer months, and occasionally into cooler months, humpback whales spend most of their time feeding and building up fat stores, or blubber, to sustain them throughout the winter.

What sets humpbacks apart is not only what they eat, but how they gather it. NOAA Fisheries describes several techniques used to herd, corral, and disorient prey, including bubbles, sounds, the seafloor, and pectoral fins. The best known is group coordinated bubble net feeding. Whales blow curtains of air bubbles to condense prey, push the prey toward the surface, and then lunge upward through the circular bubble net with mouths open. Different groups use other bubble structures in similar ways, and NOAA Fisheries notes regional specialization in bubble feeding behavior among populations.

That learned, local character matters: a population may favor herring or capelin in one region and krill in another, using the prey that is abundant nearby and the technique its group has learned.

Minke, right, bowhead, and gray whales

Minke whales are among the smallest baleen whales, and they take krill and small schooling fish, with the exact mix shifting by ocean and season. They are rorquals, like blue, fin, and humpback whales, which means they lunge feed with expandable throat pleats. A minke whale does not need the enormous gulp of a blue whale, because its body is smaller.

Right whales and bowhead whales feed more quietly: instead of gulping, they swim slowly with the mouth open, letting water flow continuously over long, fine baleen. Whale and Dolphin Conservation describes them as skim feeders. For North Atlantic right whales, copepods are the central food. Woods Hole Oceanographic Institution reports that the average adult right whale consumes about a ton of food a day, eating billions of tiny crustaceans called copepods that are packed with protein and calorie-rich oils. That figure is an average for an adult feeding whale, and it shows why right whales gather where dense copepod patches appear.

Gray whales break the surface feeding image completely. NOAA Fisheries states that gray whales are primarily bottom feeders that consume a wide range of seafloor and just above the seafloor invertebrates, such as amphipods. The whale sucks sediment and food from the seafloor by rolling on its side and swimming slowly along, filtering food through 130 to 180 coarse baleen plates on each side of the upper jaw. In doing so, gray whales often leave long trails of mud behind them and feeding pits on the seafloor. Their baleen is coarser, because it must separate small animals from sediment rather than strain tiny animals from clear water. NOAA Fisheries describes eastern North Pacific gray whales feeding in summer in the northern Bering and Chukchi seas, then migrating south to wintering and calving areas off Baja California, Mexico.

Toothed whales: hunters that find prey one at a time

Sperm whales: deep squid hunters

Sperm whales are the largest toothed whales, and their diet is built around deep water. NOAA Fisheries states that sperm whales hunt during deep dives that routinely reach depths of 2,000 feet and can last for 45 minutes. After a long, deep dive, the whale comes to the surface to breathe and recover for several minutes before the next dive. Because sperm whales spend most of their time in deep waters, their diet consists of species such as squid, sharks, skates, and fish that also occupy deep ocean waters.

Echolocation is the tool that makes that hunt possible. In dark water, sight cannot find a squid at depth. Sound can. Sperm whales produce clicks, listen for echoes, and speed up their clicks into a rapid buzz as they close on prey. Their teeth fit that hunt: NOAA Fisheries states that sperm whales have 20 to 26 large teeth on each side of the lower jaw, while teeth in the upper jaw rarely break through the gums. Those lower teeth grip slippery prey. They do not chew it into small pieces. A squid taken at depth is swallowed, often whole.

Beaked whales: suction feeders in the dark

Beaked whales are the least seen large whales, and their diet is known largely from strandings, stomach contents, and acoustic tags. NOAA Fisheries material on beaked whales describes them as deep, offshore divers that feed on small, deepwater squids and fishes using suction feeding. Because they suck prey in, they do not need teeth for gripping in the same way a sperm whale does, and females of most species have teeth that stay hidden beneath the gums throughout life.

Suction feeding does not mean weak hunting: the mouth and throat create a sudden inflow that draws prey in whole. Dives can be very long and deep, and surface time is short, which is why beaked whales are hard to study alive. The safe summary is narrow: beaked whales are deepwater squid and small fish eaters, with exact prey varying by species and by how much is known about that species.

Beluga whales: Arctic generalists

Beluga whales show how varied a toothed whale diet can be when the whale lives in shallow Arctic and sub-Arctic waters and follows seasonal fish runs. NOAA Fisheries states that beluga whales have a varied diet consisting of fish, including salmon, eulachon, cod, herring, smelt, and flatfish, as well as invertebrates such as octopus, squid, crabs, shrimp, clams, snails, and sandworms. Acoustic data, NOAA Fisheries notes, has documented the relationship between beluga feeding and the presence of spawning runs of salmon and eulachon.

Belugas also use echolocation to navigate and hunt, and they return to birth areas each summer to feed and calve. If a fish run is late, weak, or shifted, the whales that timed their feeding to that run feel it first. The beluga diet is therefore best described as opportunistic within a local pattern, not as a fixed list for every beluga.

Narwhals, pilot whales, and other toothed whales

Narwhals, close relatives of belugas, live in Arctic waters and feed on fish, squid, and other invertebrates, with prey shifting by season. Their famous tusk is a tooth, but it is not a simple biting tool, and narwhal diet summaries should stay general unless a specific population and season is named. Pilot whales, which are large oceanic dolphins rather than true baleen whales despite the word whale in their name, feed mainly on squid and fish. Smaller toothed whales, including many dolphins and porpoises, follow the same logic at a smaller scale. If it has baleen, it filters. If it has teeth, it hunts.

Killer whales: one name, many diets

Killer whales, also called orcas, deserve a short, careful section here, because they are the toothed whale most likely to confuse a reader. Taken as a whole species, killer whales have the most varied diet of all cetaceans, according to NOAA Fisheries. Different populations, however, are usually specialized in their foraging behavior and diet. NOAA Fisheries states that diet is primarily determined by the culture, meaning learned hunting tactics, of each ecotype.

In the United States Pacific Northwest, NOAA Fisheries describes residents that exclusively eat fish, mainly salmon, and transients, also called Bigg’s killer whales, that primarily eat marine mammals and squid. Offshores eat fish, including sharks. Outside the North Pacific, NOAA Fisheries notes other specializations, including killer whales off Norway feeding mainly on herring and other schooling fish, killer whales off New Zealand eating stingrays and sharks, and Antarctic killer whales eating minke whales, seals, or Antarctic toothfish, depending on type.

A killer whale that eats salmon and a killer whale that eats seals are both killer whales, but they do not eat the same diet or depend on the same prey stocks. A full account of killer whale survival will be covered separately in the companion article on what killer whales need to survive. Here, the diet point is enough: for orcas, always ask which population.

How whales actually catch food

Lunge feeding is the rorqual method: accelerate toward a prey patch, open the mouth very wide, expand the throat pleats, engulf a huge volume of water and prey, close the mouth, and push the water out through the baleen. Smithsonian reporting describes whales engulfing more than their own body weight in water in some lunges, then filtering out krill and small fish within seconds. The exact volume varies by species and prey density. A lunge costs energy, and it pays only when the patch is dense enough that one gulp contains far more calories than the lunge spent.

Skim feeding is the right whale and bowhead method: swim slowly with the mouth open, and let water flow continuously across the baleen. The cost per minute is lower, but the method only works when prey is dense enough. That is why right whales are so sensitive to prey shifts.

Bottom feeding is the gray whale method: roll on the side, move slowly along the seafloor, suck in sediment and water, and strain out amphipods. Suction feeding is the beaked whale method: expand the throat quickly, creating an inflow that draws prey in whole. Echolocation hunting is the toothed whale method for unseen prey: produce clicks, listen for echoes, and speed up into a buzz as prey is approached.

Cooperation changes what prey is available. Humpback bubble net feeding concentrates prey for a group lunge, and a killer whale pod working as a team can take prey a single whale could not. Diet is not only a property of the whale’s mouth. It is also a property of its social group.

How diet changes through the year and through life

Many baleen whales live on a feast and fast cycle. Summer feeding grounds are rich, cold, and productive. Winter breeding grounds are warm, sheltered, and poor in the prey those whales eat. The whale feeds intensively in summer, stores energy as blubber, migrates, breeds, calves, and then returns to feed again. A whale seen in warm winter water and not feeding is not necessarily starving. It is in the fasting part of its annual cycle, living on stored energy. The risk comes when the fasting period is extended by a late return to feeding grounds, a poor feeding season before migration, or extra energy costs from disturbance, entanglement, or noise.

Toothed whales do not follow the same strict feast and fast cycle, because their prey, such as fish and squid, is available more widely through the year. They still have seasonal shifts: a beluga following a salmon run, a sperm whale following deep squid fields, and a killer whale following a salmon migration are all tracking seasonal prey, even if they do not fast for months in the baleen way.

Whale calves do not start life eating krill, fish, or squid. They nurse. Whale milk is very rich in fat, and calves grow fast on it. NOAA Fisheries notes nursing periods of varying length by species, and for sperm whales it notes that calves will eat solid food before one year of age but continue to nurse for several years. A young humpback does not bubble net feed as skillfully as an experienced adult on its first attempt, and a young killer whale does not hunt seals as skillfully as an experienced pod member. Diet is learned, not only inherited.

Three reasons explain why the same species can eat different food in different oceans: prey availability differs by ocean; learned behavior differs, as killer whale ecotypes and humpback bubble net traditions show; and body size differs, so a blue whale needs dense krill patches while a minke whale can live on thinner patches.

What whales do not eat

Whales do not eat people as prey. A baleen whale cannot swallow a person in the way a cartoon suggests, and a toothed whale does not hunt humans as food. Whales do not eat plants as a main food. Baleen whales eat animals, even when those animals are tiny. Krill, copepods, amphipods, and small fish are animals, not plants. Phytoplankton, which are tiny photosynthetic organisms in the ocean, are food for krill and copepods, not directly the main food for whales. A whale that eats krill is eating animals that ate phytoplankton, and that food chain step matters, because changes in phytoplankton, ocean temperature, and sea ice can affect whales even though whales do not eat phytoplankton directly.

Whales do not eat everything they encounter. A blue whale swimming through a fish school does not automatically eat fish in large amounts, because its feeding method is tuned to krill patches. A killer whale population that eats salmon does not automatically eat seals when salmon are scarce, because its hunting culture is built around salmon. Whales also do not eat plastic, fishing gear, or debris as food, although they can ingest it by accident while feeding.

How scientists know, and why diets matter

Scientists do not guess whale diets from size alone. Stomach contents from stranded or deceased whales show what was eaten recently, but a stranded whale may not be a typical feeding whale, and soft prey may digest faster than hard parts such as fish bones or squid beaks. Fecal samples show prey DNA and hard remains, and have revealed seasonal prey shifts for some species. Tags that record depth, movement, and sound can show when a whale lunges or buzzes during a prey chase, and acoustic surveys can measure prey density where whales are feeding. For deep feeding, inference from tags, acoustics, and stomach contents carries more weight, and a responsible account should distinguish well observed feeding from inferred feeding, such as some beaked whale diets.

Whale diets also connect the ocean food web in both directions: krill and copepods are eaten by whales, and whales, through their feces, return nutrients such as iron to surface waters, where phytoplankton can use them. Diet also explains vulnerability. A specialist that depends on one prey type in one place, such as a blue whale depending on dense krill patches, is vulnerable when that prey shifts, thins, or arrives late. A generalist that can switch between krill and fish, such as a humpback, has more room to adjust, though not unlimited room. Protecting whales therefore also means protecting their food.

Frequently asked questions

Do all whales eat krill?

No. Krill are central for many baleen whales, especially blue whales, and important for humpback, fin, and minke whales, but they are not the whole whale diet. Right whales eat mainly copepods, gray whales eat mainly seafloor invertebrates such as amphipods, and toothed whales eat mainly fish and squid. Krill are a headline prey, not a universal prey.

Do whales eat fish?

Some do, and some do not in any large amount. Humpback, fin, and minke whales eat small schooling fish as part of a mixed baleen diet. Toothed whales eat fish as a main food, including salmon, herring, cod, and many other species depending on population and place. Blue whales eat fish only occasionally, according to NOAA Fisheries, and their main food remains krill.

Do whales eat sharks?

Some toothed whales do. Sperm whales eat sharks, skates, and deepwater fish as part of a deepwater diet. Some killer whale populations eat sharks as part of a varied population diet. Baleen whales do not hunt sharks. A shark eating whale is always a toothed whale, and usually a killer whale or a sperm whale, not a filter feeder.

Do whales eat seals?

Some killer whale populations do. Transients, or Bigg’s killer whales, in the Pacific Northwest primarily eat marine mammals, including seals, sea lions, porpoises, dolphins, and other whales. Other killer whale populations eat mainly fish and do not eat seals as a main food. Baleen whales do not eat seals.

How much does a whale eat per day?

It depends on species, size, feeding season, and prey density, and published figures are estimates for feeding whales, not fixed daily rations. NOAA Fisheries gives up to 6 tons of krill a day for some of the biggest blue whales, up to 2 tons of food daily for a fin whale, and about 3 to 3.5 percent of body weight per day for a sperm whale. Woods Hole Oceanographic Institution gives about a ton of food a day for an average adult North Atlantic right whale feeding on copepods. Those figures should not be averaged into a single whale daily intake, because the whales, prey, and methods differ.

Do baby whales eat the same food as adults?

No, not at first. Calves nurse on rich milk and grow fast. They begin to take solid prey as they learn to feed, while still depending on their mothers. A calf’s diet changes from milk, to milk plus learning to feed, to the adult diet of its population.

Why do whales fast during migration?

Many migratory baleen whales feed intensively in cold, productive summer grounds, store energy as blubber, and then migrate to warm breeding and calving grounds where their main prey is scarce. Fasting during that period is part of their annual cycle, not a sign that food has vanished everywhere. The risk arises when feeding was poor before migration, migration is longer or more costly than usual, or disturbance adds energy costs, so that stored energy runs low before the whale returns to feed.

Sources & references

• NOAA Fisheries. Blue Whale. https://www.fisheries.noaa.gov/species/blue-whale
• NOAA Fisheries. Fin Whale. https://www.fisheries.noaa.gov/species/fin-whale
• NOAA Fisheries. Humpback Whale. https://www.fisheries.noaa.gov/species/humpback-whale
• NOAA Fisheries. Gray Whale. https://www.fisheries.noaa.gov/species/gray-whale
• NOAA Fisheries. Sperm Whale. https://www.fisheries.noaa.gov/species/sperm-whale
• NOAA Fisheries. Beluga Whale. https://www.fisheries.noaa.gov/species/beluga-whale
• NOAA Fisheries. Killer Whale: Science. https://www.fisheries.noaa.gov/species/killer-whale/science
• Whale and Dolphin Conservation Australia. Whale facts and information. https://au.whales.org/whales-dolphins/facts-about-whales/
• Woods Hole Oceanographic Institution. To Find Whales, Follow Their Food. https://www.whoi.edu/oceanus/feature/to-find-whales--follow-their-food/
• Smithsonian Institution. Scientists discover sensory organ in baleen whales that choreographs movement of their massive jaws and throat-pouch. https://insider.si.edu/2012/05/scientists-discover-organ-in-baleen-whales-that-choreographs-movement-of-their-massive-jaws-and-throat-pouch/