Orcas—also known as killer whales—reside in oceans all over the world. These massive mammals have captivated humans for centuries. Just like any other mammal, fish, bird, reptile, or amphibian that humans study with great interest, it’s a privilege to learn more and more about them over time.
Knowledge is power, as they say, and in the case of killer whales, researchers are excited to have recently confirmed that Bigg’s killer whales are not a type of resident orca as previously declared. Rather, they are a separate species altogether, a distinction that not only highlights orca diversity but also has the potential to support new and ongoing conservation efforts.
Types of Killer Whales Around the World
According to Defenders of Wildlife, a national conservation organization, orcas are the most widespread cetacean in the world, and “there are several distinct populations . . . that vary notably in prey, genes and culture.”
Whale and Dolphin Conservation (WDC), an international charity “dedicated to the worldwide conservation and welfare of all whales, dolphins, and porpoises,” separates the different types of killer whales by hemisphere. Orcas in the Northern Hemisphere include Resident, Bigg’s, North Atlantic Type 1, North Atlantic Type 2, and Offshore, while orcas in the Southern Hemisphere are Type A, Type B (large), Type B (small), Type C, and Type D.
WDC’s website also makes a point to note that more ecotypes likely exist, and they use “tropical orca” populations as an example: these types of killer whales, they write, reside in the waters near the Hawaiian Islands and in the Gulf of Mexico and “have so few observations that it’s not even known what they feed on – they, too, could be new ecotypes or subspecies.”
Getting to Know the Bigg’s Killer Whale
Transient orcas are also commonly known as Bigg’s killer whales in honor of Dr. Michael Bigg, a Canadian scientist who was passionate about studying them. In fact, Dr. Bigg took note of the differences between transient orcas and other types of killer whales throughout his years of research.
One major characteristic that sets transient orcas apart from residents is their diet: they feed on marine mammals such as seals and porpoises. According to Wild Orca, “Southern Resident killer whales are salmon specialists: 80% of their diet is Chinook.”
Call them transient orcas or Bigg’s killer whales, but one thing is for certain: from now on, they should no longer be identified as resident orcas. It would be like calling a dog a wolf, or suggesting that cheetahs and leopards are the same because they’re both big, spotted cats. Bestowing an animal the wrong distinction overlooks their hunting techniques, habitats, social behaviors, and other genetic traits that make them unique.
Introducing a New Species of Killer Whale
An article published in March 2025 by NOAA Fisheries states that researchers began to wonder decades ago if two well-known killer whales in the North Pacific Ocean were really the same species.
“Biologists have increasingly recognized the differences between resident and Bigg’s killer whales,” the NOAA article states. “Resident killer whales maintain tight-knit family pods and prey on salmon and other marine fish. Bigg’s killer whales roam in smaller groups, preying on other marine mammals such as seals and whales.”
Their differences extend well beyond their diets and pod sizes. Take their coloration, for example: resident killer whales have “open” or uniformly gray saddle patches, while Bigg’s killer whales have “closed” saddle patches with varying amounts of black and gray pigmentation that’s often heavily scarred.
When resident orcas hunt, they use echolocation to detect prey and are known to be highly vocal; Bigg’s killer whales, on the other hand, are typically silent while foraging. These and other facts compiled by Merlin Smith and published by NOAA Fisheries reveal surprising side-by-side comparisons of these two types of killer whales.
Fascinatingly, Dr. Bigg noted as far back as the 1970s that resident orcas and transient orcas “did not mix with each other even when they occupied many of the same coastal waters.”
Given all the evidence that Dr. Bigg gathered—and that other scientists and researchers continued to gather long after his death in 1990—it can now be asserted with confidence that Bigg’s killer whales are not resident orcas; they truly are a species all their own.
The new scientific name for resident killer whales is Orcinus ater. Bigg’s or transient orcas—the new species of killer whale—has been bestowed the scientific name Orcinus rectipinnus. (If you’re curious to know how these names were chosen, check out this article.)
Celebrating the New Species of Killer Whale
It would not have been possible to have reached this conclusion about a new species of killer whale without the dedicated efforts of a team of scientists representing both NOAA Fisheries and universities who assembled “genetic, physical, and behavioral evidence.” Their data, including aerial images taken by drones, helped make the distinction between these killer whales not only obvious but also official.
The aforementioned NOAA Fisheries article further highlights the fact that “the two species likely diverged more than 300,000 years ago and come from opposite ends of the killer whale family tree. That makes them about as genetically different as any killer whale ecotypes around the globe. Subsequent studies of genomic data confirm that they have evolved as genetically and culturally distinct groups, which occupy different niches in the same Northwest marine ecosystem.”
Now that it’s undeniably clear that resident orcas and Bigg’s orcas are two separate species, there’s now enough justification to merit endangered species protections designed to help them survive and prosper. This underscores how important it is to keep studying life on earth, including marine mammals like killer whales. The more we learn, the more we understand; the more we understand, the more we can take the actions necessary to promote their survival.
Try to Spot a Killer Whale With Harbor Breeze Cruises
At Harbor Breeze Cruises, we love trying to spot different types of killer whales in the Pacific Ocean! Our daily whale watching cruises come highly recommended, especially because our tours are family friendly and affordable. Cruises depart daily, and we’d be thrilled if you joined us! Purchase your tickets online or give us a call at 562-432-4900. Our captains, crew, and Aquarium of the Pacific educators look forward to meeting you!