The most common dolphin species, the bottlenose dolphin, has a top speed of 21.7 miles per hour. The fastest member of the dolphin family is the killer whale, which can reach speeds of more than 30 miles per hour.
Dolphins' streamlined bodies are built for fast swimming, and their strong flukes and tail fins provide excellent propulsion. They use their speed to catch the fish and other marine creatures on which they feed. Dolphins' strong bodies also allow them to leap above the water. This behavior may save energy during travel, as less friction is generated when traveling through the air.