Orcas have long been categorized as a single species, although some scientists have questioned this classification in recent decades. Now, researchers propose that two orca populations in the eastern North Pacific Ocean are actually two distinct species.
In a study published March 27 in the journal Royal Society Open Science, the scientists compared two groups of orcas (Orcinus orca) — resident and Bigg's killer whales — and cited a number of distinct differences.
