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Despite its name, the killer whale is actually a type of dolphin. The killer whale is the largest of the dolphin family and is instantly recognizable to professionals and amateurs alike. It is a black dolphin with white patches near the eyes and down each side.
When killer whale calves are born, their white patches have an orange or yellow tint, but this fades to white as they grow older. They are born measuring around 8 feet in length and weighing around 400 lb (which is much larger than many adult dolphins of other species!). As they grow to maturity, adult males will reach a length of 30 feet and females will grow to 25 feet. Males can weigh over 6 tonnes and females can weigh up to 4 tonnes. Their size makes them extremely strong and earns them the title of being one of the fastest marine mammals. Adult killer whales can reach speeds of 30 knots which means that they can easily keep up with boats and some small ships.
Females reach sexual maturity at the age of 15 and give birth to a single calve after a gestation period of 12 to 14 months. In order to avoid inbreeding and to protect pods from genetic diseases, killer whales usually mate outside their own pod. Calves are born all throughout the year but only 50% of calves tend to make it to maturity.
Killer whales are found in all of the oceans of the world and are the only dolphins to live in the Arctic and Antarctic regions. They have an immensely varied diet, although scientists think that individual populations have a particular type of prey which becomes their specialty. Some populations exclusively eat fish, whereas a vast number of killer whales also hunt and kill marine mammals such as whales, other dolphins, seals and sea lions.
There is no real concern over the conservation status of the killer whale in general. They are regularly seen in all parts of the world and on the whole numbers do not seem to be decreasing. Researchers now think that there may be several species of killer whale, although they have yet to be formally identified, and for this reason their official conservation status is registered as ‘data deficient’. Although there is plenty of data on killer whales in general, as they have yet to be divided into their subspecies, this data is largely useless for conservation purposes. Certain localized populations have started to dwindle in numbers and in these instances some particular populations have been classified as endangered even though the overall species is not at risk of extinction.