Cetaceans

Lengthy juvenile periods are typical for animals of greater intelligence. In Greek myths and other ancient sources, whales and dolphins have been accorded the attributes of higher intelligence, congeniality, and kindness to humans. Observations of wild and captive dolphins supporting a dead baby dolphin at the surface for hours and days—probably an instinctive act by a naturally protective mother—are no doubt the source of long-standing anecdotes about dolphins saving injured human divers from drowning.

It is generally agreed that cetacean intelligence surpasses other non-human mammals, such as dogs, seals, and even many primates. Curiosity, affection, jealousy, self-control, sympathy, spite, and trick-playing are all common observations by human handlers of captive cetaceans. Their brains feature a sizeable and deeply convoluted cortex, suggesting considerable higher learning ability; dolphins in particular are known for their powers of innovation. An especially large supralimbic area of the brain explains their excellent powers of memory and social intelligence.

Greater communication skills often accompany greater powers of intelligence. An underwater listener in the vicinity of a group of cetaceans may be surprised by the great variety of sounds they produce, from the repetitive tonal pulses of fin whales, to the moans and knocks of gray whales, the whoops, purrs, and groans of bow-head whales, and the elaborate, eerie songs of humpbacks. Cetaceans do not have vocal cords; odontocete vocalizations are produced in a group of air sacs in the region below the blowhole atop the head, and are projected out through the melon. Mysticete sounds seem to come from an area off the lower side of the larynx, but the exact origin is unclear. Many of the social odontocetes emit whistles, and intense whistling seems to accompany excitement surrounding feeding, sex, and the joy of riding a wave before a speeding boat. Individuals may recognize one other from their unique whistles and other sounds.

Male humpback whales, who sing primarily during the breeding season, are the greatest balladeers of all cetaceans. In addition to their melodic, haunting songs, humpback whales produce a harsh gurgling noise, something like the sound a drowning person might make; their vocalizations, which may go on for hours, were audible through the wooden hulls of old whaling vessels. Superstitious sailors, hearing these voices out of the deep below their ship, believed they were the ghosts of drowned comrades, coming back to haunt their old vessel.