text: The smallest animal in this order is named for the naturalist Philibert Commerson.
full_question: The smallest animal in this order is named for the naturalist Philibert Commerson. Many animals within this order possess a mass of adipose tissue in the forehead called a melon. The closest living relatives of this extant order are the hippopotami. The carcasses of many members of this order are known as "falls," and provide a rich ecosystem in the bathyal and (*) abyssal zones. Some animals in this order have cochleae with the highest amount of innervation of any mammal, enabling them to carry out a bat-like form of echolocation; other animals in this order generate sound with the spermaceti organ. These animals breathe through a blowhole at the top of their head. For 10 points, name this order of marine mammals consisting of porpoises, dolphins, and whales.
first_sentence: The smallest animal in this order is named for the naturalist Philibert Commerson.
raw_answer: cetaceans [or Cetacea; prompt on whales before mentioned; prompt on dolphins before mentioned; prompt on porpoises before mentioned]