The Killing Kind
Not Black and White
Killer whale mystery deepens
Evolutionary development scientists, or "Evo-Devo" scientists, can have great arguments over the two types of killer whales in southern B.C. These marbled creatures are the same species – Orcinus orca – living separate lives in the same waters. One population hunts fish; the other meat. These creatures ignore each other, use different languages, and haven't interbred for thousands of years. The species simply split apart.
Origin of species
At the crux of this mystery is a big "origin of species" question. Did these intelligent creatures fracture into different groups while sharing the same waters – meaning they deliberately chose to live in different solitudes? Or were these killer whales physically separated at some point in their evolution – meaning geography and isolation created different types of killer whales?
| Interesting fact: Other animals can tell the difference between the killer whales. A seal will swim alongside the fish-eating resident killer whales, knowing it is safe. But it will rightly flee for its life from the silent and deadly transients. |
Did something change in their cells or genes? Today, very slight physical differences separate these killer whales. The transients have a more triangular dorsal fin and a more uniform saddle patch. But it's a subtle difference. Most humans wouldn't be able to tell the killer whales apart.
Mysterious mothers
Did the females cause the split? Both the residents and transients travel in family pods led by the oldest female, or matriarch. The resident matriarchs command large pods of a dozen or more. The transient matriarchs break their families into much smaller groups – usually just three in a hunting party. (Presumably, these small, quieter groups allow them more stealth to surprise unsuspecting prey.)
Do these matriarchs determine the evolution of B.C. killer whales? Do they steer their families away from other killer whales? If so, why? To avoid a fight? Or maybe to keep their hunting grounds secret from the other killer whales, and provide as much food as possible for their own families?
| Interesting fact: Scientists spotted a rare all-white killer whale in Alaskan waters in February 2008. It was a healthy adult male, nine metres long and weighing about 10,000 pounds. |
More twists in this mystery – Four populations of killer whales in B.C.
British Columbia's large coastline actually supports four distinct populations of killer whales. The southern residents summer in lower B.C. and Washington State. The transients share these same waters while travelling along the Pacific coastline. An offshore population cruises the open ocean, hunting fish, sharks and sea turtles. And in B.C.'s North Coast, about 200 northern resident killer whales hang around Johnstone Strait and the Queen Charlotte Islands.
Why the four solitudes?
B.C. killer whales maintain strict, separate identities. This, in itself, is not uncommon for killer whales. Killer whales inhabit every ocean on Earth and each population has developed differently, with varied vocalizations and diet preferences.
But in southern B.C., the transient and southern resident killer whales share the exact same waters. That makes the dramatically different evolution infinitely mysterious.
Scientists can only guess what happened thousands of years ago.
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