Quick answer
Blue whales filter krill — up to about 4 tonnes on a feeding day. They are baleen mammals, not sharks. Never feed wild blue whales. Species IUCN Endangered (2018). Figures checked 13 August 2026.
What do blue whales actually eat?
Krill. “Carnivore (krill)” without the lunge and the 4-tonne feeding-day figure was the template line. They do not take fish the way toothed whales do, and they do not take people.
How do blue whales feed?
They lunge through a swarm, gulp, and press water out through baleen. Calves drink milk, not krill. Lean seasons mean travel and fasting on blubber, not a broader menu of sharks’ leftovers.
What do they do to the food web?
They recycle nutrients by taking vast krill volumes and defecating in surface water. Empty swarms cannot hold them. Diet conservation is krill-and-shipping conservation.
Is the conflict about food?
No. Never feed wild blue whales. The lethal overlap is ships and gear on feeding grounds, not a whale raiding a harbour. A calf gaining tens of kilograms a day on milk is not a pet-food problem.
Does size change the menu?
It locks it. The largest animal known still runs on krill. A tongue the mass of an elephant does not switch them onto tuna. Size is why a strike is so often fatal — not a reason they “must” eat large prey.
Why eat something so small?
Because dense swarms repay a lunge. WARN’s donate page funds wildlife-protection partners — not whale research ships.
Sources
Blue Whale FAQs
What do blue whales eat?
Almost entirely krill, filtered through baleen after lunging through dense swarms. On feeding days they can take up to about 4 tonnes. They are baleen mammals, not sharks, and not a fish-and-squid porpoise. Never feed wild blue whales. Species IUCN Endangered (2018).
Do blue whales eat people?
No. The throat and baleen are built for krill, not for swimmers. Ship strikes go the other way. Do not approach a surfacing whale or a calf. A “carnivore” label without krill is the template error this page used to make.
Do they eat the same things as whale sharks?
Overlap on tiny prey, different animal. Whale sharks are filter-feeding fish on plankton, eggs and small fish. Blue whales lunge on krill — up to about 4 tonnes on a feeding day. Mixing the menus mixes the class — and the Antarctic CR subspecies with a snorkel hotspot.
How does diet link to conservation?
They feed where krill is dense, which is also where ships run. Empty swarms cannot hold an Endangered lunge-feeder. Ship strikes and entanglement still cut the recovery. World Animal Rescue Network’s donate page funds wildlife-protection partners — not whale research ships.
Who this page is for.This page is about wild diet. Skip it if you need a captive feeding plan from a veterinarian.