by L.S. Watts

Created on: June 11, 2009   Last Updated: June 14, 2009

The orca is known by many names. Some of these include blackfish and seawolf, but it is most commonly known as the killer whale. Its scientific name is Orcinus orca. Many people think of the orca as a whale, but it is actually a dolphin because it belongs to the family Delphinidae.

Appearance

The killer whale is predominately black with a white chest and some white on the sides. It also has white patches around the eyes. It has a large dorsal fin with a gray patch at the rear of the fin.

The killer whale is considered the largest, and quite possibly the oldest, in the thirty-five species of dolphin. The males can grow to 19-26 feet long weighing 6 tons. The females are slightly smaller growing to only 16-23 feet and weighing only 3-4 tons. Even calves are born 6-8 feet long and weighing around 350-500 pounds.

Males tend to have a larger pectoral fins and dorsal fin than the females. In fact, the dorsal fin can be twice the size as a female's fin and more triangular in shape.

Life Cycle

Females reach sexual maturity around 15 years of age and will no longer be able to produce young at 40 years of age. Males are sexually mature at 15 years, yet many don't reproduce until around 21 years of age. Once a female becomes pregnant, the gestation cycles takes approximately 15-18 months. In most cases, only one calf is born and the female won't be ready for impregnation again for another 5 years. The mother will nurse the calf for 24-months even though the calf can eat solid foods at 12-months old. However, the mortality rate for calves is rather high and only half will make it to 12-months.

Many females only live to around 50 year, but some have known to thrive and live for 70-80 years. Male, however, only live about 30 years but have been known to live as old as 60 years. Killer Whales in captivity tend to have shorter life spans compared to those in the wild.

Social Structures

Killer Whales live in groups called pods. The general size of a pod is five to thirty orcas. However, pods in the Antarctic and off the coast of Alaska have been seen in the hundreds. Sometimes pods of fifty or more are called herds or aggregations. Female and juvenile orcas tend to stay in the center of the pod while the males are on the outskirts.

Not all orcas travel in pods that have males. Some travel in maternal groups made up of mothers and their calves. Many times they are all related. Even still there are cases where these maternal groups are simply subpods swimming not too

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