Killer whale

Orcinus orca

Appearance

Size: 5.5 - 9.8m

Key feature: Black in colour with brilliant white patches

The killer whale, or orca, is one of the most familiar and well known cetaceans. Contrary to what the name suggests the killer whale is actually a dolphin, and is the largest member of the dolphin family. It is easily recognisable with its distinctive black and white pattern on its body. It has a black body with a white patch behind its eye, a white chin and underbelly and a white/grey “saddle” behind its dorsal fin. The intensity of the black and white varies between different populations. The males are particularly recognisable with their tall, straight dorsal fins, whilst the females have a shorter, more curved fin.

Behaviour

Killer whales are sociable and inquisitive creatures, travelling in groups of 2 – 50. They are fast and active, often demonstrating breaching, crashing and spy-hopping behavours. They have a relatively small, bushy blow, only visible at close range. Despite the nickname killer whale, they have never been known to show aggression to humans in the wild, and rarely amongst themselves. The name originates from the nickname “Whale killer” given to them by fishermen after observing killer whales hunting larger species of whales in groups. 

Distribution

Killer whales have a global distribution and are one of the most widespread cetaceans. They are often found in shallow waters where they have been known to partially beach themselves to catch seals, but are also found in large numbers in deep offshore waters. They exist in different populations which rarely interbreed; it is possible that several species exist. In the UK they can be seen most regularly around the Shetland and Orkney Islands. They are occasionally encountered on the Bay of Biscay survey trips and their known range covers all of ORCA’s survey routes, although they are not frequently encountered. It has been recognised that their are different ecotypes of killer whales that differ morphologically biologically with different specialised hunting strategies seen between the different ecotypes.

Threats

Live killer whales were once captured in large numbers for aquariums and sea parks and although there are still a number of individuals in captivity throughout the world this number has significantly declined in the last two decades. Killer whales were kept in captivity for commercial and scientific purposes, although several high profile fatal incidents involving marine mammal trainers over recent years has damaged the public perception of the industry. Currently in the wild killer whales are at risk from pollution and depletion of their prey. They also suffer when chemical contaminates build up lower down in the food chain, this level of pollution accumulates with each step up the food chain and when large numbers of contaminated prey are consumed by top predators, such as killer whales, contaminants reach dangerous levels, affecting their long term survival.

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