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Shark Info 2 / 98   (11-15-1998)

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  Intro:

Shark Accidents or Shark Attacks? 1/2

Shark Info

  Main article:

Shark attacks - an ever intriguing puzzle

Dr. E. K. Ritter

  Article 1:

Shark attacks in the Mediterranean

Ian K. Fergusson

  Article 2:

How much do you know about sharks and shark accidents?

Shark Info


Shark attacks - an ever intriguing puzzle

By Dr. Erich K. Ritter

Sharks are one of the best adapted vertebrates in the oceans and have a large number of highly developed senses. In addition to perceiving acoustic, optic and scent stimuli, they can also sense changes in water pressure and bioelectrical fields. No other marine animal can compete with sharks when it comes to their senses, which makes them quite unique. And through these extraordinary capabilities, they can analyze the individual stimulus field of each marine organism.

Sharks as objects

On many fishing boats sharks are treated as "objects" - not as living beings - and are heaved on board with questionable methods.

© Shark info

Nature teaches us that organisms which developed in the same environment can recognize and classify each other properly. In the long history of evolution the animals thus adapted themselves to each other and learned to adjust their behavior to one other. Such development always takes place over thousands or even millions of years until at some point it becomes "instinct". Fish, seals, dolphins and other creatures of the sea thus react very specifically to sharks and vice versa. A successful and meaningful interaction takes place between organisms which developed in the oceans. However, things which are not part of ocean life either cannot be analyzed or can only be analyzed to a minimum degree. Since humans are not ocean animals, a shark cannot "recognize" what a human being is, he can only employ his senses in the framework of what he is used to seeing. So he tries to identify man using his sense of smell or sight, or bioelectrically. In most cases, a shark will react to a human, a reaction which, however, does not mean he has recognized a human, but rather is attempting to identify an unknown object with his available senses.

In this way - even when the investigated object is not of marine origin - the shark may possibly react to a visual or acoustic impulse or an electrical field so that an object may resemble an organism he already knows. A diver in a black suit will hardly smell like a seal, but maybe his appearance and bioelectrical field will somehow remind the shark of a seal and prompt him to approach the diver. The shark does not simply assume that the diver is really a seal, he only recognizes the diver as being an object which resembles a seal. Since he cannot completely analyze what he has seen, and since he cannot definitely exclude that it may be something edible, the shark may bite and test the edibility of the object with his taste buds. Whether or not he "likes" the object tasted then becomes the final criteria which makes him either eat the potential prey completely or release it.

Accidents are not mistakes

When talking about accidents with surfers, we mostly address "mistakes" made by the shark, in other words, it is a foregone conclusion that the shark mistook the surfer for a seal. This theory has prevailed over many years because from a human standpoint, it sounds so plausible and conveniently confirms the commonly held false opinion that sharks are primitive animals. This explains why the mistake appears to be the real cause of the accident. Yet, viewed more critically, the apparently so plausible "cause of the accident" is nothing more than a welcome solution. Sharks are not dumb eating machines! On the contrary, they are very intelligent creatures. If we use common criteria to define intelligence - such as learning, remembering, or also reacting in unknown situations - then sharks are second to none even compared to higher ranking animal groups. If we add the relationship between brain and body mass as a criteria, then sharks can even be compared with many mammals - which, after all, is the animal group to which we humans belong!

The evolution of the sharks took approximately 400 million years and at the moment finds its climax in today's living shark species. During this long period of time, they had to cope with many other animal groups. It is highly unlikely that sharks - as the currently so dominant animal group in the marine environment - could build up their hunting strategy on the basis of "mistakes". If this were true, they would have been extinct a long time ago, having represented only a "whim of nature".
All too many times our anthropocentric viewpoint deludes us into believing a wrong idea. Man's attempt to explain a situation from his point of view may be natural and understandable, yet in behavioral biology it is a perilous approach. We humans first register our environment using our eyes. Thus, automatically, we try to explain a shark's attack on a surfer by primarily using our sense of sight. Sharks, however, possess many more senses which they use to analyze such an encounter with a surfer. This fact must be considered when interpreting any shark accident. Often we simply judge sharks too quickly and produce old theories whch have been making the rounds for years. Sharks do not bite by mistake! And a bite does not result because the shark, for example, has mistaken a diver for a seal. A shark bites because he wants to assess something which he is not familiar with by means of his taste buds.

The following question must therefore be posed: Looking at the situation worldwide, why do so few surfers get bitten by sharks? Surfers are something completely new for every white shark, so each encounter should result in the shark biting the surfer which means the beaches would have to be completely covered with bitten up surfboards. The explanation lies in the shark's evolution into a top hunter of the seas. The unknown is always potentially dangerous and - even for the shark - harbors a certain risk. Approaching or biting the unknown object is thus an exception and not the rule!

Blood - the universal substance which triggers shark attacks?

If we were to ask people on the street what the best stimulus is to trigger a shark attack, the reply "blood" would surely be the most frequent answer. This apparently universally accepted opinion is equally prevalent with both laymen and experts alike. For most people, "blood in the water" is equivalent to "feeding frenzies" of sharks, a mistaken explanatory mechanism similar to the "shark-surfer phenomenon". However, that which is believed to be so obvious need not be "the wisest solution". No two blood types are the same! The blood of every animal species has a specific, individual composition consisting of plasma proteins, anorganic ions and salts, organic nutrients and nitrogen waste products, to name just a few. Research shows that sharks possess extremely sensitive smelling organs which developed over millions of years and make them react to proteins rather than sugar. But even with its highly specialized sense of smell the shark can only identify animals which he already knows based on their blood composition. Certain elements in the blood may remind him of familiar organisms and thus trigger an approach maneuver. Still, the shark knows exactly that the blood which he smells is not completely familiar to him and will near the object very cautiously.

Using the term "feeding frenzy" thus becomes questionable when the assumption is made that this behavior is supposedly induced by the smell of blood. Latest research shows that such "frenzied eating rituals" are more likely connected to a fast-moving hierarchical eating pattern rather than any disorganized fighting. Although blood may help to accelerate certain forms of behavior, it neither intoxicates the shark's senses, nor does it deliver compelling evidence for a real "frenzy". But just like the so-called "mistaken biting" of surfers, the supposed effects which blood has on sharks has also become an established opinion which has far too long been supported uncritically by the media.

Old ingrained theories must be reexamined

Following World War II, a committee was established and assigned the responsibility of developing a shark repellent. In order to better understand a shark's manner of attack, all "attack" data was collected and evaluated. Nevertheless, attention was always focused on the event itself, and the animal's biology was neglected.
This shortsighted way of thinking has persisted up until today. Accidents are still analyzed primarily from this viewpoint, only accompanied by a description of external factors which seemingly lead to these incidents, such as blood, noise, appearance, etc. So in order to find the real causes of the accident, and in order to avoid another senseless massacre of sharks out of fear, lack of understanding or desire for profits, or in order to better explain them, everything must be done to steer research in the direction of including shark biology and behavior in such investigations.
For the broad masses the shark still mainly represents a dumb incapable monster which bites by mistake. Many people would even find it a blessing if these animals no longer swam in the oceans. Campaigns for the protection of sharks are thus built on shaky grounds. But the truth is that sharks are a central and vital component when it comes to maintaining the balance of the oceans and must thus be preserved with all available means. Proper understanding of the real reasons for shark accidents would thus help to considerably improve their bad image, and could also mean a long overdue improvement of man's own image.

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* Dr. Erich K. Ritter is a shark biologist and adjunct assistant professor at Hofstra University, New York (USA)

May be published only by indicating the source: Shark Info / Dr. Erich K. Ritter



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