A dolphin's forelimbs are pectoral flippers. Pectoral flippers have all the skeletal elements of the forelimbs of terrestrial mammals, but they're foreshortened and modified. The skeletal elements are rigidly supported by connective tissue. Thick cartilage pads lie lengthwise between the bones. Pectoral flippers are curved slightly and pointed at the tips.
Dolphins use their pectoral flippers mainly to steer and, with the help of the flukes, to stop.
Blood circulation in the flippers adjusts to help maintain body temperature. Arteries in the flippers are surrounded by veins. Thus, some heat from the blood traveling through the arteries is transferred to the venous blood rather than the environment. This countercurrent heat exchange aids dolphins in conserving body heat. Each lobe of the tail is called a fluke.