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Sunday, November 20, 2011
Are Sharks Afraid Of Dolphins?
It is often said to be a sign of good luck and protection.
The belief is that sharks fear dolphins and porpoises that can easily defend themselves against the apex predators - and will, in turn, protect swimmers, their mammalian friends.
Experienced escort pilots of channel swimmers throughout the Pacific, from the Catalina Channel to the Hawaiian Islands, also back up this understanding.
But is it true?
According to Peter Klimley and David Ainley who wrote a book Great White Sharks: The Biology of Carcharodon carcharias, Great white sharks attack dolphins and porpoises from above, behind or below to avoid being detected by the friendly mammal's echolocation. The targeted species include dusky dolphins, Risso's dolphins, bottlenose dolphins, Humpback dolphins, harbour porpoises, and Dall's porpoises.
This discomforting information is supported by Michael Heithaus who presented his study, Predator–prey and competitive interactions between sharks (order Selachii) and dolphins (suborder Odontoceti): a review" in the Journal of Zoology (Cambridge University Press). "White, tiger, bull and sevengill sharks are probably the major predators on nearshore cetaceans, but dusky sharks may also represent a risk. The risk that nearshore cetaceans face from sharks will vary with location. For example, the risk of shark predation is probably higher in tropical waters than in higher latitudes because of the diversity and abundance of large, predatory sharks in warm waters."
Heithaus, who directs the Shark Bay Ecosystem Research Project in Shark Bay, Western Australia, encourages further study of the natural relationship between sharks and dolphins where more information and understanding about the nature of shark-dolphin interactions is needed.
A MythBusters episode on the Discovery Channel explored the question, Are Sharks Afraid of Dolphins?:
Copyright © 2011 by Open Water Source
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Open Water Swimming Magazine
Open Water Swimming MagazineThe Open Water Swimming Magazine is the monthly magazine entirely focused on open water swimming heroes and heroines of every age, ability, and background. Published by the World Open Water Swimming Association, the Open Water Swimming Magazine is a free benefit to WOWSA members.
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The Other Shore
The Other Shore follows world record holder and legendary swimmer Diana Nyad as she comes out of a thirty-year retirement to re-attempt an elusive dream: swimming 103 miles non-stop from Cuba to Florida without the use of a shark cage. Her past and present collide in her obsession with a feat that nobody has ever accomplished. At the edge of The Devil’s Triangle, tropical storms, sharks, venomous jellyfish, and one of the strongest ocean currents in the world, all prove to be life-threatening realities. Timothy Wheeler’s documentary brings Diana Nyad’s extraordinary adventure to life as Diana sets out to prove that will and determination are all you need to make the unimaginable possible.
2014 Open Water Swimming Almanac
An Almanac for Open Water SwimmingAn almanac is essentially a body of knowledge which is so complete that it enables people in different fields to make predictions about the future of their respective industries.
This, for example, was the purpose of the traditional farmers almanacs. It enabled farmers to determine as accurately as possible which crops to plant for the greatest harvests in a given year.
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The trends are very clear.
The tide is rising for open water swimming.