Physical Characteristics

The killer whale’s scientific name Orcinus orca is derived from the Latin word orcas, meaning “cask” or “barrel,” referring to the animal’s broad, rounded shape. Unlike most dolphins, male and female killer whales exhibit considerable differences in size and appearance. Adult males, known as bulls, can reach up to 9.8 m (32 ft) in length and weigh over 5,500 kg (12,100 lb). Adult females, known as cows, are smaller, growing to 8.5 m (28 ft) in length and weighing as much as 3,800 kg (8,400 lb).

Both male and female killer whales have bold black-and-white coloring. The animals are glossy black over most of the body, with a white belly and striking white patches above the eye. The shape of a fainter grayish-white patch just behind the dorsal fin is unique to each killer whale and scientists use this marking as one way to identify individual animals.

The killer whale has a round, blunt head. Large powerful jaws are lined with 46 to 50 spikelike teeth adapted for ripping and tearing prey but not for chewing. A prominent triangular dorsal fin extends from the middle of the back. This fin is particularly large in adult males, growing to 1.8 m (5.9 ft) tall. The dorsal fins vary in appearance among individual killer whales—they may be curvy, twisted, flopped over, or even scarred from run-ins with boat propellers. Scientists use dorsal fins to help identify individual animals. The flippers of killer whales are broad and paddle-shaped, and the flukes (horizontal lobes on the tail) sometimes curl downward, especially in adults. Both the flippers and tail flukes of adult males are considerably larger than those of adult females.

Killer whales have a thick layer of blubber (body fat) that lies just beneath the skin. This layer of fat insulates the animal, enabling it to maintain a body temperature that ranges from 36.4° to 38°C (97.5° to 100.4°F), even in the most frigid waters.

Like all mammals, killer whales breathe with lungs. Air enters the lungs through a single blowhole located on the top of the head. At the water’s surface, the killer whale inhales and closes a muscular flap covering the blowhole before diving underwater. The animal opens its blowhole and exhales just before reaching the surface of the water.

Killer whales are among the fastest animals in the sea, reaching swimming speeds of up to 50 km/h (30 mph) for short periods of time. While underwater, killer whales can dive to depths of around 61 m (200 ft). During a dive, the animal’s heart rate slows from 60 beats per minute to 30 beats per minute. Oxygen-carrying blood is shunted away from the extremities and channeled toward the heart, lungs, and brain, where more oxygen is needed. These adaptations enable the animal to conserve oxygen while underwater.