Wednesday, April 4, 2012

Animal Mass Suicide and the Lemming Conspiracy

Ticked off Norway lemming doesn't like gossip!
Photo from Wikimedia Commons by Frode Inge Helland 
We all know the story: Every few years, millions of lemmings, driven by a deep-seated urge, run and leap off a cliff only to be dashed on the rocks below and eventually drowned in the raging sea. Stupid lemmings. It’s a story with staying power: short, not-so-sweet, and to the rocky point.

But it is a LIE.

And who, you may ask, would tell us such a horrendous fabrication? Walt Disney! Well, technically not Walt Disney himself… Let me explain:

The Disney Studio first took interest in the lemming mass suicide story when, in 1955, they published an Uncle Scrooge adventure comic called “The Lemming with the Locket” illustrated by Carl Barks. In this story, Uncle Scrooge takes Huey, Dewey and Louie in search of a lemming that stole a locket containing the combination to his vault … but they have to catch the lemming before it leaps with all his buddies into the sea forever. Three years later, Disney further popularized this idea in the 1958 documentary White Wilderness, which won that year’s Academy Award for Best Documentary Feature. A scene in White Wilderness supposedly depicts a mass lemming migration in which the lemmings leap en masse into the Canadian Arctic Ocean in a futile attempt to cross it.




In 1982, the fifth estate, a television news magazine by the CBC (that’s the Canadian Broadcasting Corporation), broadcast a documentary about animal cruelty in Hollywood. They revealed that the now infamous White Wilderness lemming scene was filmed on a constructed set at the Bow River in Canmore, Alberta, nowhere near the Arctic Ocean. Lemmings are not native to the area where they filmed, so they imported them from Churchill after being purchased from Inuit children for 25 cents each. To give the illusion of a mass migration, they installed a rotating turntable and filmed the few lemmings they had from multiple angles over and over again. As it turns out, the lemming species filmed (collared lemmings) are not even known to migrate (unlike some Norwegian lemmings). Worst of all, the lemmings did not voluntarily leap into the water, but were pushed by the turntable and the film crew. Oh, Uncle Walt! How could you?!

Norway lemmings really do migrate en masse, but they don't commit mass suicide.
Drawing titled Lemmings in Migration, in Popular Science Monthly Volume 11, 1877.
As far as we know, there are no species that purposely hurl themselves off cliffs to die en masse for migration. But, strangely enough, North Pacific salmon do purposely hurl themselves up cliffs to die en masse for migration. And what, you may ask, is worth such a sacrifice? Sex, of course!

Migrating sockeye salmon thinking about sex.
Photo from Wikimedia Commons by Joe Mabel.

The six common North Pacific salmon species are all anadromous (meaning that they are born in fresh water, spend most of their lives in the sea and return to fresh water to breed) and semelparous (meaning they only have a single reproductive event before they die). After years at sea, salmon swim sometimes thousands of miles to get to the mouth of the very same stream in which they were born. Exactly how they do this is still a mystery. Once they enter their stream, they stop eating and their stomach even begins to disintegrate to leave room for the developing eggs or sperm. Their bodies change in other ways as well, both for reproduction and to help them adapt to fresh water. They then swim upstream, sometimes thousands of miles more, and sometimes having to leap over multiple waterfalls, using up their precious energy reserves. Only the most athletic individuals even survive the journey. Once they reach the breeding grounds, the males immediately start to fight each other over breeding territories. The females arrive and begin to dig a shallow nest (called a redd) in which she releases a few thousand eggs, which are then fertilized by the male. They then move on, and if they have energy and gametes left, repeat the process with other mates, until they are completely spent. If the females have any energy left after laying all their eggs, they spend it guarding their nests. Having spent the last of their energy, they die and are washed up onto the banks of the stream.

Now that’s parental commitment! So the next time your parents start laying on the guilt about everything they’ve given up for you, share this nugget with them and remind them it could be worse…


Want to know more? Check these out:

1. Learn more about semelparity here

2. Learn more about salmon reproduction at Marine Science

3. And learn even more about salmon reproduction with this awesome post by science blogger and Aquatic and Fishery Sciences graduate student, Iris. Her current blog posts can be found here.

4. Ramsden E, & Wilson D (2010). The nature of suicide: science and the self-destructive animal. Endeavour, 34 (1), 21-4 PMID: 20144484

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