Each lobe of a dolphin's tail is called a fluke . Like the dorsal fin, flukes have no bone or muscle inside. A dolphin uses the powerful muscles along its back and tail stalk to move its flukes up and down. This motion moves the dolphin forward through the water. As it swims, a dolphin uses its pectoral flippers to steer and, with the help of the flukes, to stop.
Pectoral flippers are a dolphin's forelimbs.
Dolphins have no hind limbs, only ver small hip bones buried deep in the pelvic muscle and tissue. A dolphin breathes through a single blowhole , located on top of its head. A muscular flap covers the blowhole, making a watertight seal when dolphins dive. To take a breath, dolphins contract the muscular flap. When dolphins relax the muscles, the flap stays tightly closed.