| |
We once thought that one killer whale was just like another. But scientists have learned that it’s not so black and white. In fact, every killer whale in B.C. lives in one of three separate groups. Except for a slight difference in the shape of their dorsal fins, the whales in each group look a lot alike. Once you start watching them carefully, however, you’ll see that they act very differently.
Scientists call the three groups - or ecotypes - residents, transients, and offshores.
The three ecotypes eat different types of food, hang out in different kinds of groups, have different home territories, and even have their own “languages”. Residents are chatty fish eaters who always live with their mothers, transients are stealthy hunters who stalk seals and dolphins, and we don’t know much about the elusive offshores.
No one knows how the ecotypes formed, but it’s becoming clear that they don’t mate or interact with each other. Learning what each group needs to survive and thrive is an important part of the research at the Vancouver Aquarium.
This chart shows some of the ways the ecotypes differ:
|
Residents |
Transients |
Offshores |
Food |
Fish, particularly salmon |
Seals, porpoises, sea lions, whales and other marine mammals |
Unknown, but probably includes fish and squid |
Social grouping |
Family groups called matrlines; residents stay in the same group their entire lives |
Small groups of 2-6 whales that may change members |
Unknown; usually seen in groups of 20-60 |
Range |
Along the B.C., Washington, Orgeon and Alaska coasts
MAP |
Along the entire Pacific coast of Canada and the United States, from California to Alaska
MAP |
Usually out at sea, far from the coast |
Dorsal fin shape |
Rounded at the tip, with a sharply curved angle at the back of the tip |
Pointed tip |
Rounded at the tip, without the angle at the back |
|
|
