What Is the Delphinidae Family of Animals?

Delphinidae is the family of animals commonly known as the dolphins. This is the largest family of cetaceans.Members of this family are commonly called dolphins or delphinids.

The Family Delphinidae includes such recognizable species as the bottlenose dolphin, the killer whale (orca), the Atlantic white-sided dolphin, Pacific white-sided dolphin, spinner dolphin, common dolphin, and pilot whales.

Dolphins are vertebrates and marine mammals.

Origin of the Word Delphinidae

The word Delphinidae comes from the Latin word delphinus, meaning dolphin.

Delphinidae Species

Cetaceans in the Family Delphinidae are Odontocetes or toothed whales. There are 38 species in this family. 

Characteristics of Delphinidae

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The Delphinidae are generally fast, streamlined animals with a pronounced beak, or rostrum. 

Dolphins have cone-shaped teeth, an important characteristic that distinguishes them from porpoises. They have one blowhole, which distinguishes them from baleen whales, which have a pair of blowholes. 

Dolphins also use echolocation to find their prey. They have an organ in their head called a melon which they use to focus clicking sounds which they produce. The sounds bounce off objects around them, including prey. In addition to its use in finding prey, delphinids also use echolocation to communicate with other dolphins and to navigate.

How Big Are Dolphins?

According to the Encyclopedia of Marine Mammals, the Delphinidae can range in size from about 4 or 5 feet (e.g., Hector's dolphin and the spinner dolphin) to about 30 feet in length (the killer whale, or orca).

Where Do Dolphins Live?

Delphinids live in a wide range of habitats, from coastal to pelagic areas. 

Dolphins in Captivity

Dolphins, especially bottlenose dolphins, are kept in captivity in aquaria and marine parks. They are also kept in some facilities for research. Some of these animals are once-wild animals that came into a rehabilitation center and were unable to be released.

The first marine park in the U.S. was Marine Studios, now known as Marineland. This park began exhibiting bottlenose dolphins in the 1930's. Since dolphins were first displayed in aquaria, the practice has become more controversial, with activists and animal welfare advocates especially concerned about the stress levels and health of captive cetaceans, especially orcas.

Dolphin Conservation

Dolphins are also sometimes the victims of drive hunts, which have grown more widely known and controversial. In these hunts, dolphins are killed for their meat and to be sent to aquariums and marine parks.

Even before that, people advocated for the protection of dolphins, who were dying by the thousands in nets used to catch tuna. This led to the development and marketing of "dolphin-safe tuna."

In the U.S., all dolphins are protected by the Marine Mammal Protection Act. 

_{References and Further Information}

• _{Committee on Taxonomy. 2014. List of marine mammal species and subspecies. Society for Marine Mammalogy, Accessed October 31, 2015.}
• _{Perrin, W. F., Wursig, B., and J.G.M. Thewissen, editors. Encyclopedia of Marine Mammals. Academic Press.}