cetacean (large aquatic carnivorous mammal with fin-like forelimbs no hind limbs, including: whales; dolphins; porpoises; narwhals)
the answer is not "who" but actually "what are" Cetaceans are marine mammals
The blue whale.
Dolphins, whales, and porpoises.
The term cetacean refers to whales and dolphins. Humans belong to another category called primates.