Whale Cetaceans

Whales are generally classed as predators, but their food ranges from microscopic plankton to very large animals.
Toothed whales eat fish and squid which they hunt by use of echolocation. Orcas sometimes eat other marine mammals, including whales.
Baleen whales such as humpbacks and blues feed only in arctic waters, eating mostly krill. They imbibe enormous amounts of seawater which they expel through their baleen plates. The water is then expelled and the krill is retained on the plates and then swallowed. Whales do not drink seawater but indirectly extract water from their food by metabolizing fat.