Killer Whale – Orcinus orca
The killer whale, orca or blackfish as it is variously known is social, intelligent, powerful and an apex predator. These whales are more closely related to dolphins than other whales with their closest relative being the snubfin dolphin. Growing up to 9.8m long and 10 tonnes in weight these massive mammals are powerful swimmers and can be seen leaping from the water. Much like their dolphin cousins the orcas are a highly social and vocal species travelling in groups of 2 - 50. It has been observed that adult killer whales teach younger ones the skills of hunting, demonstrating their keen intelligence.
These whales earned their name from fishermen for being the apex predator in most regions they inhabitant with a diet of squid, octopus, fish, seals, sharks, dolphins and even other whales. Despite the name, killer whales are not considered a threat to humans, with no reports of attacks in the wild.
Recent research comparing DNA and morphological traits of killer whales in the UK suggests that there are two distinct types with differing physical and ecological characteristics. Although these two types seem to overlap geographical their feeding habits appear to differ. The first type feed mainly on fish such as herring or mackerel and are largely opportunistic feeders. The second type are more specialised with their main prey being other cetaceans. It is possible within the next few years that Orcinus orca will be split into a number of different species or subspecies.
Due to their intelligence and impressive size there is a history of killer whales being taken into captivity throughout the world. The film ‘Black Fish’ released in recent years documents this controversial practise in response to the deaths of three trainers and investigates the consequences of keeping and training these animals in captivity.
In the UK killer whales are most commonly seen north and west of Scotland in every month of the year but the peak sightings occur in June and July in Shetland’s coastal waters. Further research is required to determine the population strength of killer whales in the waters around Scotland. However like many other cetaceans, sightings have reduced dramatically in Clyde waters in the last few decades, probably due to the poor state of the local Clyde ecosystem. Killer whales are protected under UK and EU law and with a change in fisheries management allowing the Firth of Clyde to recover, we could hope to see the large, distinctive, knife like dorsal fins of killer whales breach the surface of the waters around Arran more often.
Latin name: Orcinus orca
Habitat: Ranging from warm tropical waters to the freezing polar regions. Killer whales can survive in most water temperatures.
Distribution: Globally one of the most widespread cetaceans. In the UK most commonly sighted around Shetland, Orkney and west coast Scotland.
Size: Up to 9.8m long and 10 tonnes in weight.