Adult males are 7-10 m long and weigh 4½-10 tons and females are 5½-8½ m and 2½-7½ tons.  The head is large and the flippers are paddle like.  The large dorsal fin of the males, sometimes two metres long and mostly straight, is by some considered to be a sexual sign.  The upper body is black, the underside is white, and there are white patches behind the eyes.  The teeth are 40-56 and cone shaped.  Life expectancy is 100 years.

The killer whales roam all the world’s oceans.  In the North Atlantic, they are mainly to be found north of 40°N and migrate to the ice edge in the Arctic in summer.  They are sometimes seen off the West Greenland coast, but rarely off the east coast of North America.  They seem to mate the whole year round, the gestation period is 12-16 months, and the calf weighs 180 kg and is 2-3 m long at birth.  The females reach puberty at 8-10 and the males at 16.

The killer whales are almost omnivorous.  They eat many species of seals, smaller and larger whales, giant skates, fish, squid, octopus, birds etc.  When larger whales are on the menu, they attack in number.  They are very sociable and are commonly seen in family groups and sometimes shoals of 100 animals occur.  They are found in coastal waters as well as in the open seas.

Their usual migrating speed is 10-15 km/hour, but they can easily reach 50 km/hour, when necessary.  They probably do not dive any deeper than 1000 m.  During summer and autumn they are very common off the Icelandic coast and follow schools of herring and capelin into the bays and fiords.  Their world population is unknown.