You may have heard that dolphins and porpoises are the same animal. In fact, they are not. Dolphins tend to have cone-shaped teeth. Porpoises have spade-shaped teeth. A dolphin's dorsal fin is usually curved or hooked, while a porpoise's is triangular. As of November 2026, the Society for Marine Mammalogy's April 2026 list counts 38 species of ocean dolphins and 7 species of porpoises. Both groups are toothed whales.

Dolphins find things by making sounds that bounce off objects and return as echoes. This is called echolocation. A dolphin's forehead holds a waxy, lens-shaped part called the melon. The melon focuses the dolphin's clicks into a beam. The dolphin picks up the echoes through its lower jaw. Some dolphins also find fish by listening for the sounds the fish make.

Dolphins are very intelligent animals. They are social animals that live and play in groups. A bottlenose dolphin group often breaks apart and re-forms with different members. Each bottlenose dolphin develops its own signature whistle. Scientists think that a signature whistle works like a name.

A baby dolphin is called a calf, and it drinks its mother's milk. A bottlenose dolphin calf drinks milk for about 18 to 20 months. A calf swims close beside its mother, which may help it cut down on drag. A calf usually stays with its mother for 3 to 6 years.

Dolphins eat fish, squid, and shrimp. They work together to herd fish into a group before they feed. Some bottlenose dolphins hit fish with their tails, which is called fish-whacking. Dolphins do not chew their food. Most of it is swallowed whole.

Some bottlenose dolphins live for more than 50 years. Scientists tell dolphins apart by the nicks and notches on their dorsal fins. Large sharks are the main natural predators of bottlenose dolphins. Dolphins often swim near the front of ships. They ride the waves the boats make.

In the United States, bottlenose dolphins are protected by the Marine Mammal Protection Act of 1972. Feeding wild dolphins is harmful. It teaches them to come close to boats and people. As of November 2026, people should stay at least 50 yards (46 meters) away from wild dolphins.

Words to know

• porpoises: dolphin's cousin
• melon: forehead lump
• echolocation: finding by echoes
• signature: one's own
• predators: hunting animals