A small revolution in the classification of killer whales! American and Canadian biologists have identified two new species of these cetaceans in British Columbia. Why is this so cool?
“Because since the first taxonomic mention of killer whales by the Swede Linnaeus in 1758, specialists have recognized only one species: Ursinus orca “, recalls Philip Morin, a researcher at the Southwest Fisheries Science Center in La Jolla (California) and co-site of this discovery. Published in Royal Society Open Science In March 2024.
One of these two new species is Bigg's orca, or Ursinus rectus, which constitute a group of nomads developing around Vancouver Island. The other is orc scammon, or Orsinus Ater, divided into two groups called “resident” populations in the north and south of the same island. These two species differ in size, pigmentation, distribution, diet, and genetics.
Thus, Big Orca whales are more powerful and larger: 7.1 m and 4.7 tons for females and 8.3 m and 6.6 tons for males. Their prey? Marine mammals.
Orca Scammon whales, which are the thinnest, are only 7.2 meters long. They eat only fish, such as salmon. The subpopulation inhabiting northern Vancouver Island and that inhabiting the south constitute a single species. “Not even two subspecies, even though they don't meet and have different dialects!” says Thomas Jefferson, co-author of the study and a cetacean taxonomist at the Southwest Fisheries Science Center in La Jolla.
“Killer whales [de l’île de Vancouver] It is the most studied in the world, continues Philippe Morin. However, we had to collect a lot of data to reach these conclusions. » We're talking about decades of observations, field studies, genetic analyzes and anatomical comparisons on stranded cadavers!
“Our study could serve as a model for describing other species or subspecies of killer whales,” hopes Thomas Jefferson. However, the main obstacle will be a lack of data. »
In fact, the fourth population of killer whales on Vancouver Island, which live offshore the Pacific Ocean, is of interest to scientists. “Does it constitute a species? We lack the data to determine this, regrets the researcher. However, I believe that with the necessary efforts, we will soon be able to identify other species of killer whales, especially within about ten groups that have already been identified. »
The next step: convincing the Marine Mammal Society's taxonomy committee to accept this split within the genus Orsinus.
