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What is a feeding frenzy?

f-shark-feeding-frenzy

By Blaise Jones

Nothing encapsulates the popular image of sharks more than the feeding frenzy. The thought of dozens of mouths gnashing and gnawing in food-induced madness just below the surface of the water personifies everything people fear about sharks. But why do sharks engage in this violent behavior? Is there a deeper meaning to it? Or is it simply mindless violence as so many people believe it to be?

What is a Feeding Frenzy?
A feeding frenzy is when a group of sharks feeding upon the same food source begin to act hyper-aggressively. This is usually characterized by thrashing movements, wild biting, and even shark-on-shark attacks. The animals appear to be driven mad by the food and try and devour everything around them. During these frenzies sharks appear to be completely unaware of their surroundings or any sensation other than the urge to feed. There have even been reports of sharks continuing to feed during a frenzy even after they have suffered mortal wounds at the teeth of other frenzied sharks.

Organized Chao
Not every gathering of sharks is a feeding frenzy, however. It is common for spectators to mistake normal shark predatory behavior for a feeding frenzy. Sharks may hunt together in large groups, each individual attracted to the same food source by their senses. While their movements are fast and violent, there is an order to these hunts. Sharks will swim in one at a time and attempt to catch fish before jetting out of the other side of the school. The only time there’s any shark-on-shark violence is when a subordinate animal attempts “to cut in line.” A dominant shark will not hesitate to bite and attack a subordinate shark that attempts to feed on the prey before the dominant shark has had his turn..

The agitated actions of fish caught in nets are a prime example of supernormal stimuli, one of the major factors in a feeding frenzy.
The agitated actions of fish caught in nets are a prime example of supernormal stimuli, one of the major factors in a feeding frenzy.

Supernormal Stimuli
While some observed feeding frenzies occurred naturally, many photographed frenzies are the result of abnormal circumstances. Most feeding frenzies have been observed by fishermen and whalers during their harvests. Fishery and whaling harvests create a huge amount of sensory commotion in the water that can be sensed by every shark for miles. Hundreds of thousands of fish struggling, panicking, bleeding, and dying sends out massive signals to attract predators for miles, some of them sharks.

This is called “supernormal stimuli” and is the leading theory as to why feeding frenzies occur. It’s thought that a shark is driven into a frenzy by having every aspect of its sensory system blasted to maximum capacity by the signals fish and whale harvests send out. In this overwhelmed state, normal shark predatory behavior degrades into the violence witnessed in photographed frenzies. It would be inaccurate to describe it as “mindless” however. A feeding frenzy can be compared to shoppers on Black Friday, each extra-aggressive to get their share of a limited amount of goods and they are willing to fight other extra-aggressive competitors who each want a share of the goods. The actions of both the aggressive shopper and the aggressive feeding shark are not mindless at all, merely exaggerated due to “supernormal stimuli.”

Additionally, sharks are not the only animal species that participate in feeding frenzies. In fact, nearly every animal species will participate in a feeding frenzy whenever there are many competitors for a prized prey in a relatively small area.

A carp feeding frenzy.
A carp feeding frenzy.

SOURCES:
“Sharks: The Animal Answer Guide” by Gene Helfman and George H. Burgess

“The Encyclopedia of Sharks” by Steve Parker

http://animals.howstuffworks.com/fish/sharks/shark-feeding-frenzy.htm

http://www.elasmo-research.org/education/topics/s_pain.htm