Whales are carnivores, meaning that they subsist entirely on a diet of meat. Whales are part of a larger order of animals called cetaceans, which also includes dolphins and porpoises. All cetaceans are carnivorous animals.
The type of meat consumed by cetaceans can vary from microscopic zooplankton to other whales, including the blue whale, the largest animal on Earth. Cetaceans are broken down into two types: mysticeti and odontoceti, or baleen and toothed whales, respectively.
Baleen whales have overlapping plates of a fingernail-like substance, called keratin, that are used to filter zooplankton and other small animals from the seawater, ranging from krill to seabirds, though the latter is generally considered bycatch for baleen whales. There are 12 species of baleen whales that are divided into four groups, including: right, pygmy right, rorqual and gray.
Toothed whales, such as sperm whales, dolphins and porpoises, have either conical or spade-shaped teeth used for grabbing and trapping prey, such as fish, squid and even other marine mammals. For example, killer whales, the largest dolphins in the world, have been observed hunting marine mammals, including blue whales, dolphins, porpoises, seals, sea lions and walruses, in addition to its typical diet of fish and squid.