Killer whales are members of the scientific family of toothed whales called Delphinidae, the dolphin family. The killer whale is the largest member of the dolphin family. Killer Whales are easily recognized due to their striking black and white coloration, and a sleek, streamlined, fusiform (tapered at both ends) body shape.

The rounded and paddle-like forelimbs are pectoral flippers which are used mainly to steer and, with the help of the flukes, to stop.
The dorsal fin acts as a keel and probably helps stabilize a killer whale. The dorsal fins of male killer whales are the tallest of any cetacean in the world, growing up to 1.8 m (6 ft.). Female dorsal fins are smaller at about 0.9 to 1.2 m (3-4 ft.) and may be slightly curved back.

Male killer whales, or bulls, begin maturing at 12 to 14 years of age and over the next few years, grow very quickly and attain physical maturity at about 20 years. Most males probably reach a length of 8 to 9 metres. Females, or cows, average about 7 metres in length and reach reproductive maturity at about 14 to 15 years. The gestation period is 16 to 17 months. A single calf is usually born (although twins have been recorded). Killer Whales calves are about 2.5 metres long at birth and weigh approx 200 kilograms. Newborn killer whales nurse for at least one year. The mortality rate of calves is quite high - over 40% of resident calves die in their first six months.

Killer whales often hunt cooperatively in pods for food. They work together to encircle and herd prey into a small area before attacking. When hunting a large whale, a pod of killer whales may attack from several angles (generally transients).

The conical and interlocking teeth of killer whales are well suited for a wide variety of prey, from small schooling fish to large whales. The number of teeth varies among individuals - but there are usually 10 to 14 teeth on each side of the jaw, a total of 40 to 56 teeth. Each tooth is about 7.6 cm (3 in.) long and approximately 2.5 cm (1 in.) in diameter.

Adult killer whales eat approximately 3% to 4% of their body weight in food per day, fully weaned calves can eat up to approximately 10% of their body weight during growth periods.
Killer whales can also be distinguished by the kinds of underwater communication sounds they produce - squeals, squawks, and screams are used for social communication within and between groups. Killer Whale clans, like dolphins, can be distinguished by their different dialects. Killer whales have acute hearing and also acute vision both in and out of the water.

Echolocation enables them to locate and discriminate objects by projecting high-frequency sound waves and listening for echoes. Killer whales echolocate by producing clicking sounds and then receiving and interpreting the resulting echo. Killer whales live in groups called pods. A pod may consist of as few as five and as many as about 30 individuals: a mix of males, females, and calves of varying ages. Sometimes, several smaller pods join together to form larger herds of 50 or more whales. Some researchers believe that the lifespan of a killer whale is about 25 to 35 years, but no one knows for certain.