Cetacean diets: who eats what?

Specialists or generalists?

Some cetaceans are highly specialised predators: Cuvier’s beaked whale eats almost nothing but squid, the resident killer whale eats fish (mainly Chinook salmon), the blue whale 99% krill. Others are opportunists: the common bottlenose dolphin takes fish, cephalopods and crustaceans alike. This overview presents the diets of 20 species and their characteristic hunting techniques.

Further reading on feeding

Diet shapes the whole ecology of a cetacean. Explore also the anatomical counts (teeth vs baleen), the thermal and bathymetric preferences, the catalogue of hunting behaviours, and the energy consumed each day.

Specialists and opportunists: trophic diversity

Cetacean diets cover almost the whole marine spectrum. Antarctic krill (Euphausia superba) feeds most of the large baleen whales of the southern hemisphere. A major study published in Nature by Savoca et al. in 2021 revised the classical estimates upwards: an adult blue whale swallows on average ~16 tonnes of krill a day during the Antarctic feeding season, about three times more than earlier estimates drawn from the stomach contents of hunted whales.

Odontocetes specialise: the sperm whale swallows ~750 squid a day, among them sometimes giant squid (Architeuthis), in encounters documented by the healed sucker marks on its skin. The killer whale shows culturally specialised ecotypes: fish-eating residents (Chinook salmon), mammal-eating transients (seals, porpoises, young whales), shark-eating offshores (sharks, rays). This trophic specialisation is so stable that it is coming to be recognised as speciation in progress.