June 10 – With Great Porpoise

Today’s factismal: Orcas are the largest dolphins which makes them the largest of the smallest whales.

An orca patrols in the Salish Sea (My camera)

An orca patrols in the Salish Sea
(My camera)

Nature is confusing. Where people like to draw clean lines separating this from that, nature tends to smear things together. Dust becomes rubble becomes planets becomes stars. A pile of dirt becomes a hill becomes a mountain. And an individual becomes a subspecies becomes a species becomes a genus becomes a family. For an example of that last, let’s consider the orca, known popularly as a “killer whale”.

A mother orca and her baby swim in the Puget Sound (My camera)

A mother orca and her baby swim in the Puget Sound
(My camera)

If you ask the average armchair taxonomist about the orca, they will quickly point out that the orca is actually a dolphin and therefore isn’t a “real” whale. As usual, the armchair taxonomist is flat wrong. In history, dolphins were separated from “true whales” based mostly on their size; a typical dolphin is about as big as a human but a typical whale is as big as a whale. However, once you start looking at the biology, things get a little more complicated.

Whales
For example, the dwarf sperm whale is just nine feet long and weighs just 550 lbs while the bottlenose dolphin can reach 13 feet long and weigh as much as 1,400 lbs. And the beluga whale is 18 feet long and weighs 3,500 lbs while an orca is up to 30 feet long and weighs as much as 8,000 lbs. So clearly calling something a whale or a dolphin is more a matter of custom than biology.

Orcas frolic in the Salish Sea (My camera)

Orcas frolic in the Salish Sea
(My camera)

Of course biologists prefer to avoid the question entirely and refer to dolphins, whales, and the often overlooked porpoises all as cetaceans which translates literally into “whales”. And once they’ve done that, they break the cetaceans into those like the blue whale that filter-feed (the mysticeti or “baleen whales”) and those like the orca that chomp down to chow down (the odontoceti or “toothed whales”). As a result, the lines that the biologists draw are somewhat more in line with nature’s. And one of the ways that the biologists are drawing the lines is with the sounds made by the orcas. By listening to different groups of orcas in the Salish Sea, biologists hope to discover more about how orcas live and interact. To help them with this work, all you need is a computer and a pair of ears. You’ll listen to sound files from under the sea and then tell the biologists what you heard. To learn more, swim over to:
http://www.orcasound.net/

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