A new type of killer whale that preys on large mammals including dolphins and elephant seals has been discovered in the US.
The species, which were found on the west coast, have been named "outer coast transient whales" by Canadian researchers.
They also hunt baby grey whales and prefer to stalk their prey in the Pacific's deepwater canyons, instead of hunting close to sure.
The whales have a unique vocal dialect and are believed to be a part of a larger group of transient orcas known as Bigg's killer whales.
But for decades, it has been assumed that any mammal-eating killer whale found near southeast Alaska to Southern California came from a single west coast population of transients, reports Hakai Magazine.
"Killer whales are found all over the world," says Josh McInnes, a master’s student at the University of British Columbia, who led the study.
"They spend most of their time in coastal waters, but we’re now finding that they do inhabit the offshore oceanic waters. And there’s basically nothing known about them out there.
"When you look at the open ocean, you can’t see anything but water," says McInnes.
"But below the surface, deep down, there is a whole interesting bathymetry that supports life."
Scientists studied more than 100,000 photographs taken off the Canadian and US west coasts and of the 150 encounters from 2006 to 2018, the majority of the new killer whales were observed in the offshore waters between Oregon and central California.
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It was reported that only 26 have ever been seen in the coastal waters of the northeast Pacific.
Aside from having unique dietary preferences, outer coast and nearshore transient killer whales were also found to have distinct dialects.
Scientists highlighted that the calls of some outer coast killer whales are higher pitched than their cousins.
"I think it’s really exciting," Lawrence Dill, a behavioural ecologist at Simon Fraser University told Hakai Magazine.
"Top predators are so important to the functioning of ecosystems.
"It’s important to understand where these different groups of orcas are potentially having impacts that would transmit through entire communities."
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