Tuesday, August 21, 2012

Great White Versus Orca

This incident happened a few years ago. National Geographic later did a one hour piece on the whole relationship between orca, aka killer whales, and great white sharks in the Farallon Islands, off San Francisco.


Orca dining on a Great White



In this video, a tourist boat comes across an orca swimming with its calf.  Then, a great white shark came along.  The next thing the tourists saw was the orca coming to the surface holding the shark upside down in its jaws.  The shark never had a chance.

Two interesting bits of understanding emerged from this incident.

Interesting bit #1 - Researchers have long known that turning a shark upside down induces a form of torpor,  rendering the shark totally defenseless.  The scientists knew this, but this incident appears to prove that at least some orcas know it as well and use it in their hunting technique with sharks.

Interesting bit #2 - The orca killed the shark at a time of year when there were a lot of seals in the area. Because of that, lots of great white sharks were also there, looking to score a seal for dinner.  Some scientists were working in the Farallons with tagged great whites at the same time the shark was killed by the orca. The scientists recorded some totally unexpected behavior. The great whites took off. In one case, a radio tagged shark dove deep and fled the area. It didn't stop until it was thousands of mles away.  Somehow, the sharks seemed to know one of their own had been killed.  The mechanism remains unknown, but, at a time of year when the waters around the Farallons are normally teeming with great white sharks feasting on seals, there were no sharks to be found.

I just thought this whole episode was fascinating. If the tourist boat hadn't been on scene when the orca killed the shark; if that incident had not been witnessed,  shark researchers would still be trying to figure out why all the other great whites in the area suddenly dissappeared. 

Here is the link to the video that shows the orca dispatching the Great White Shark..

http://www.youtube.com/watch?v=XbQ5qCJEEwc&feature=related






No comments:

Post a Comment