The killer whale, or orca, is the largest member of the dolphin family. Its size, striking black and white colouring, and tall dorsal fin are unmistakable. Males reach lengths of 8 or 9 metres and weigh up to 5 tonnes. Females are smaller at 7 metres and 4 tonnes. Killer whales are mainly black above and white below, with an oval white patch behind each eye. In adult males, the paddle-shaped flippers are very large and the tips of the tail flukes curl down. The first sight of a killer whale is usually its dorsal fin. In fully grown males, this fin sticks straight up, often as high as 1.8 metres. In females and young whales, the fin is curved and less than one metre high. Behind every dorsal fin there is a gray area called a saddle patch. The shape of the dorsal fin and the saddle patch, as well as natural nicks and scars on them, are unique to each killer whale. By photographing the dorsal fin of killer whales, researchers can tell individual whales apart.