Cetacean intelligence
Cetacean intelligence is the overall intelligence and derived cognitive ability of aquatic mammals belonging in the infraorder Cetacea (cetaceans), including baleen whales, porpoises, and dolphins. Brain Size Brain size was previously considered a major indicator of the intelligence of an animal. However, many other factors also affect intelligence, and recent discoveries concerning bird intelligence have called into question the influence of brain size. Since most of the brain is used for maintaining bodily functions, greater ratios of brain to body mass may increase the amount of brain mass available for more complex cognitive tasks. Allometric analysis indicates that in general, mammalian brain size scales at approximately the or exponent of body mass. Comparison of actual brain size with the size expected from allometry provides an encephalization quotient (EQ) that can be used as a more accurate indicator of an animal's intelligence. Sperm whales (Physeter macrocephalus) have the largest known brain mass of any extant animal, averaging 7.8 kg in mature males. Orcas (Orcinus orca) have the second largest known brain mass of any extant animal. (5.4-6.8 kg) Bottlenose dolphins (Tursiops truncatus) have an absolute brain mass of 1,500–1,700 grams. This is slightly greater than that of humans (1,300–1,400 grams) and