As in the flukes and the flippers, arteries in the dorsal fin are surrounded by veins to help conserve body heat in cold water. It is located at the center of the back. Teeth are conical and interlocking. The number of teeth varies considerably among individuals. A bottlenose dolphin may have as many as 98 conical teeth.
Eyes are on the sides of the head, near the corners of the mouth.
See also eyesight. Glands at the inner corners of the eye sockets secrete an oily, jellylike mucus that lubricates the eyes, washes away debris, and probably helps streamline a dolphin's eye as it swims. A single blowhole, located on the dorsal surface of the head, is covered by a muscular flap. A bottlenose dolphin breathes through its blowhole. The bottlenose is relaxed in a closed position.