Cetacean intelligence

Cetacean intelligence is the ability to think and solve problems shown by aquatic mammals called cetaceans. This group includes baleen whales, porpoises, and dolphins. These animals live in the water and have surprised scientists with their smart behaviors.

In 2014, a study found that the long-finned pilot whale has more special brain cells than any other mammal studied, including humans. This shows how clever these ocean animals can be. Scientists are still learning more about their amazing minds.

Brain

Size

Brain size used to be thought of as a big clue to how smart an animal is. But now we know there are many other things that affect intelligence too, like how the brain works.

When we look at how big an animal's brain is compared to its body, we can get a better idea of how smart it might be. This is called the brain to body mass ratio. Some dolphins, porpoises, and whales have a higher ratio than humans, meaning their brains are bigger compared to their body size than ours are.

• Sperm whales have the biggest brains of any living animal.
• Orcas come next.
• Bottlenose dolphins have brains that are a bit more than human brains and about four times bigger than chimpanzees.

Structure

In 2014, scientists found that a type of dolphin called the long-finned pilot whale has more cells in a special part of the brain than any other animal studied so far, including humans. Dolphin brains are different from land animals because they have a special area that might help them process sounds and feelings.

Dolphins also rely more on sound than sight, so the part of their brain that handles sound is much bigger than the part that handles sight.

Brain evolution

The brains of cetaceans, such as whales and dolphins, have grown larger and more complex over time, similar to the brains of primates.

Scientists think this growth may have happened because these animals need to manage large and complex social groups. Other factors, like changes in their food, the development of echolocation, or needing to travel farther, might also have helped shape their brains.

Problem-solving ability

Some studies show that dolphins can understand ideas like numbers, even if they can't count exactly. They can tell different numbers apart.

Researchers who study how animals learn to recognize groups often say that dolphins are about as smart as elephants. Dolphins are very good at learning, but they are not smarter than some other clever animals.

Behavior

See also: Whale § Life history and behavior

Dolphin groups can be different sizes. River dolphins usually stay in small groups of about six to twelve, and they know each other well. Some dolphins, like the pantropical spotted dolphin, common dolphin, and spinner dolphin, travel in much larger groups of hundreds. These big groups can move together when they sense danger, showing they work as a team.

Orcas in British Columbia, Canada, and Washington, United States, live in family groups led by an older female. These groups stay together for a long time and have their own special sounds to talk to each other. Bottlenose dolphins also form strong groups, with females connecting directly or through friends, and males forming teams to help each other.

Dolphins love to play, making bubbles and rings underwater and enjoying the shapes they create. They have helped humans in need and can learn new tricks. Some dolphins have used tools, like wrapping sea sponge around their noses to protect themselves while searching for food.

Communication

Further information: Whale vocalization and Human–animal communication

Whales and dolphins use sounds to talk to each other and sense their surroundings. Toothed whales, like dolphins, make three main types of sounds: clicks, whistles, and pulsed calls.

• Clicks are quick sounds made to find out about objects around them using echoes.
• Whistles are used to talk to each other, like a special call for each dolphin.
• Pulsed calls are used by some whales, like orcas, and have special tones and patterns.

Dolphins can learn human sign language and understand simple sentences. They remember each other's whistles even after many years apart, showing they have very good memories.

Self-awareness

Self-awareness is an important ability that helps animals think about their own actions, just like humans do. Scientists believe that bottlenose dolphins, along with elephants and great apes, may have this ability.

One way scientists test for self-awareness is by using a mirror. They put a mark on an animal and see if it recognizes itself in the mirror. Dolphins have been shown pictures of themselves on television and seemed to understand it was them, which suggests they might be self-aware. However, some scientists think more tests are needed to be sure.