Dolphins: Delphinidae

Dolphins are highly intelligent social animals. Many species appear to live in cooperative groups, groups that work together. They may live in groups called pods of fewer than five or as many as several thousand. To some extent, group size depends on the availability of food. Within a large group, animals often separate by age and sex.

Dolphins have excellent hearing and communicate with each other by producing a variety of different sounds, often identified as "clicks," "pulses," and "whistles." Some of these sounds may be identifiers for individual animals, but this communication is not well understood. Dolphins living in clear water may also communicate by flipping and flashing patches of color on their bodies.

There are many examples of dolphins working cooperatively. They may work together to locate and round up a school of fish or chase them into shallow water or to attack a predator, an animal that hunts them for food. They have been seen helping newborn or injured animals to the surface to breathe. They are best known for their acrobatics. They often leap and spin out of the water, sometimes in large, coordinated groups. They are curious and playful. Some dolphins will catch a ride on the waves a boat makes as it passes through the water. Dolphins can be taught behaviors or tricks when in captivity.

Dolphins mate and give birth in the water. From an early age, both sexes do a lot of touching and stroking, rubbing and sex play behavior with their own and the opposite sex. Sexual maturity, the ability to reproduce, occurs when individuals are between five and sixteen years old. Larger species tend to mature later than smaller ones. A single calf is born after a pregnancy lasting ten to fifteen months.

The bond between mother and calf is extremely important and may last many years. Calves begin to catch fish when they are a few months old, but may continue to nurse for three-and-a-half years or more. Even after they are weaned, no longer nursing, they remain with their mother for a year or longer.