Cetacean intelligence

In 2014, a study found that the long-finned pilot whale has more neocortical neurons than any other mammal, including humans, examined to date.

[3] Allometric analysis indicates that in general, mammalian brain size scales at approximately the 2⁄3 or 3⁄4 exponent of body mass.

[24] In 2014, it was shown for the first time that a species of dolphin, the long-finned pilot whale, has more neocortical neurons than any mammal studied to date including humans.

It has also been suggested that similar to humans, the paralimbic region of the brain is responsible for a dolphin's self-control, motivation, and emotions.

[28] This result has been interpreted to mean that dolphins sleep only one hemisphere of their brain at a time, possibly to control their voluntary respiration system or to be vigilant for predators.

[29] Sensory experiments suggest a great degree of cross-modal integration in the processing of shapes between echolocative and visual areas of the brain.

[32] As far as which selective pressures drove the encephalization (or decephalization) of cetacean brains, current research espouses a few main theories.

This means that the dolphins must be aware not only of their near neighbors but also of other individuals nearby – in a similar manner to which humans perform "audience waves".

One hypothesis proposed by Jerison (1986) is that members of a pod of dolphins are able to share echolocation results with each other to create a better understanding of their surroundings.

[39] Southern resident orcas in British Columbia, Canada, and Washington, United States, live in extended family groups.

The basis of the southern resident orca social structure is the matriline, consisting of a matriarch and her descendants of all generations.

[44][45] In bottlenose dolphin studies by Wells in Sarasota, Florida, and Smolker in Shark Bay, Australia, females of a community are all linked either directly or through a mutual association in an overall social structure known as fission-fusion.

Alliance composition is stable on the order of tens of years, and may provide a benefit for the acquisition of females for mating.

They also appear to enjoy biting the vortex-rings they have created, so that they burst into many separate normal bubbles and then rise quickly to the surface.

This was studied by Karen Pryor during the mid-1960s at Sea Life Park in Hawaii, and was published as The Creative Porpoise: Training for Novel Behavior in 1969.

On each occasion the experiment was stopped when the variability of dolphin behavior became too complex to make further positive reinforcement meaningful.

[53] At the Institute for Marine Mammal Studies in Mississippi, it has also been observed that the resident dolphins seem to show an awareness of the future.

However, one dolphin, named Kelly, has apparently learned a way to get more fish, by hoarding the rubbish under a rock at the bottom of the pool and bringing it up one small piece at a time.

[52] As of 1984[update], scientists have observed wild bottlenose dolphins in Shark Bay, Western Australia using a basic tool.

When searching for food on the sea floor, many of these dolphins were seen tearing off pieces of sponge and wrapping them around their rostra, presumably to prevent abrasions and facilitate digging.

[citation needed] The environment where dolphins live makes experiments much more expensive and complicated than for many other species; additionally, the fact that cetaceans can emit and hear sounds (which are believed to be their main means of communication) in a range of frequencies much wider than humans can means that sophisticated equipment, which was scarcely available in the past, is needed to record and analyse them.

The contrasting pigmentation of the body may be used, for example with "flashes" of the hypopigmented ventral area of some species, as can the production of bubble streams during signature whistling.

Phoenix and Akeakamai, bottlenose dolphins, understood individual words and basic sentences like "touch the frisbee with your tail and then jump over it".

Each dolphin has a unique whistle that functions like a name, allowing the marine mammals to keep close social bonds.

Scientific research in this field has suggested that bottlenose dolphins, alongside elephants and great apes, possess self-awareness.