Who's afraid of sharks???

They arrived 150 million years before dinosaurs and they have stayed virtually unchanged for the last 200 million years. These fearless creatures are masterpieces of evolution, no room for improvements. Unlike man, they are not pondering on the purpose of their life, they are fulfilling it.

It's Coming!
I put a mask on my face, let ten meters of rope into the water, filled my lungs with fresh tropical air and dived into the Big Blue. Surrounded by clear mid-ocean water the yacht, attached to the other end of the rope, pulled me through Timor Sea. I was a few meters below surface and suddenly felt an urge to look back. Just as well, as there was a frighteningly familiar creature behind me, a Shark! Silvery grey, pointed snout, pectoral fins slightly downward and coming straight toward me! It was impossible to estimate the distance in the clear open ocean. I instantly turned to look at the blurred shape of the yacht in front of me. My only thought was "up!" Within seconds, my mask was down to my neck. With an unpleasant tingling in my toes, my hands did their best to drag me up. I recalled the little reef shark that we had caught on a hook a couple of days before. "It's the revenge of the ocean" - I thought. I felt like a bait on a hook.
A few seconds later I was standing (and shaking) on the deck, watching a 2,5 meter Tiger Shark circling the boat. (I thought they did that only in Hollywood movies) It was time to re-evaluate my concept of sharks and their behaviour.

Shark -The Man eater?
Are sharks cold-blooded killers or just misunderstood film stars? It is hard to get accurate information about shark attacks on humans. There is a lot of talk about them and many stories written, but the scientific validity of them is hardly stronger than that of the Genesis. Shark attack statistics, like all statistics, require cautious interpretation. The same goes for any published information. Published writing, including this one, is the view of one writer, based on the material and experience that he or she has on that subject. Journalist Steve Boyer tells a story in Xavier Maniguet's book "Jaws of Death": 
"A news agency receives the following dispatch from a small local newspaper: "Is the population boom in seals attracting more sharks?"  The next day another paper uses the story with a headline: More seals may mean more sharks". Next version of the same story was: "Experts declare that the seal population is attracting more and more Great White Sharks..." A few days later a regional paper is writing: "Great White Sharks infest Santa Barbara waters". Finally, a week later another newspaper had a headline: "Sharks and seals attacking divers..." " 
Although statistics are (fortunately) not made from newspaper stories, they do have the tendency of being misinterpreted. People regard statistics as the absolute truth, without questioning the methods of data collection. In 1958 a Shark Attack File was established in the Smithsonian Institution in Washington, US. It suggests that less than 100 attacks occur every year, world wide, less than 20 of them fatal. How accurately this corresponds to reality, remains a mystery. Shark Attack File remains the most comprehensive file ever made on shark attacks around the globe and it is often the source of information for encyclopedias, books and TV documentaries. A closer analysis of the file reveals that a great deal of the information is based on stories from people who weren't at the scene of the attack! From statistics we get an impressive amount of numbers but it helps us little to understand the factors and circumstances that led to an attack. An active scuba diver will be poorly comforted by the fact that more people are struck by lightning than killed by sharks. Surely the possibility of a shark-attack is pretty remote when standing in a cane field!

If you watch a TV documentary on sharks, you hear horror music in the background. The screen is filled with great jaws in a feeding frenzy. The program surely becomes more entertaining if the camera crew equips itself with a bucket of blood and fish guts. If the script follows the highlights of the famous Spielberg film, the real information is just as surely being buried in a bloody excitement. So what about the truth then?

The Masterpiece of Evolution
There are nearly 400 species of sharks in the oceans. They range from 15cm (Squaliolus laticaudus) to 15meters (Whale Shark). Thirty-five species have been known to attack people but only a dozen are regarded as a potential danger to man. As scuba diving and other water activities are becoming increasingly popular, more people are forced to confront their shark phobias. Knowledge is power and to understand these magnificent creatures better, I suggest we jump in their shoes and look at the world from their point of view. 
Now, free your imagination and become a shark for a few minutes. We choose one of the Chacharhiniformes, the group of sharks that includes most of the species dangerous to man. Before you close your eyes and sink your teeth into your mother-in-law's groin, picture yourself into the assembly line of evolution. Let's see how you'll be equipped to rule your domain. 
You will be wearing material that is more bone than skin. Covered with thousands of tiny teeth, similar to the ones in your jaws, your skin becomes a weapon in itself, capable of inflicting wounds by a simple rub against your prey. The sense of touch is standard equipment but as you're flying the F-18 of the oceans, you get a whole range of special gimmicks. Instead of five, you will be equipped with eight extraordinary senses, each one supporting one another in a perfect harmony. Your eyes have an enhanced night vision mode, being 10 times more sensitive to light than human eyes. You will see colours and detect changes in contrast four times quicker than man. Your ears have a simple structure, which gives you the sense of balance as well as an accurate hearing distance of more than 2 km. 
To support your hearing, evolution equips you with a lateral line, tiny pores running in a line from head to tail. These nerve endings will outdo any dive computer in their accuracy of sensing pressure. Lateral line, together with your ears, is sensitive to low 20-40Hz frequencies and it can easily detect the smallest movements of any nearby fish.
The most accurate sense after hearing is your smell. Your nostrils will be filled with odours that flow continuously through two independent pairs of openings. Because of two separate smell sensations, you can choose your directions toward the stronger aroma. The sense of taste in ones mouth is a pretty ordinary thing to have. But as a shark you are no ordinary piece of fish. How about a few thousand taste buds scattered around on your back? Called the Pit organs, these tiny nerve masts are located in the cavity of overlapping "skin-teeth" (denticles) and they measure the changes in chemical composition of the surrounding water. Like lateral line, they operate from a distance of 100-200 meters, complementing the sense of vibrations and smell. 
As you are to become the masterpiece, evolution spares you with a unique tool, a sense exclusive to sharks, and sharks only: "The Ampullae's of Lorenzini". These are nerve endings located in your snout and serve a multiple of purposes, most unique of them being the detecting of small variations in electric field around you. The accuracy of this sophisticated sense is almost beyond human comprehension. With this organ you can not only detect the heartbeat of stingray buried in the sand but also feel the change in earth's magnetic field when you do long distance navigating. 
To find your prey is not enough, you also need to have the tools to kill and eat it. So you get even more instruments. Not many men go and sharpen their razors these days, they simply replace the blade. Sharks discovered this convenient method over 200 million years ago, not for shaving purposes though. As your razor-sharp teeth are put to heavy use and no dentists are available, you will be granted a special permission to grow teeth in several rows. (No other animal does it) A new row of teeth is grown every 2-6 months and a broken tooth is replaced instantly by rolling out the next one on the line. 
Your eating gear is then placed in a hydrodynamic frame, powered not with a floppy tail fin, but the whole body. Your "engine" will have two gears. The first is a layer of red muscles that are using oxygen and are capable of keeping you in constant motion night and day. The second is a layer of white muscles that use stored glycogen and accelerate you to speeds more than 50km/h. With outstanding agility and a fearless mind you are now ready to fill your purpose: To remove the sick and the weak. (Slightly over equipped I would say...)


Only One Bite....
Shark is no evil creature and it does not choose its prey by its name. It is simply an incredible combination of senses working in perfect harmony. It is an amazingly successful animal devoted to its mission; keeping the fish population strong and healthy.
From its senses we can determine that it is more than capable of finding its prey. From its power we know that it can bite a turtle like a biscuit. What we want to know is how to avoid being one of its meals. 
The shark is patrolling the sea with all of its eight senses. Like a security guard, it checks out everything that is unusual. (Many sharks are active at night) It is basing its behaviour on sense data. As hearing is its most sensitive tool, it will often come around following attractive noises. Anchoring a boat, splashing of several swimmers or divers or the sound of a boat engine often brings sharks from the neighborhood to investigate. When it reaches 500 meters from the source of noise, it will start to get smell sensations to help it to determine the attractiveness of the scene. If no smell is detected, it often disappears. If there is blood or other appealing odour in the water, the shark is able to determine its direction quickly and accurately. The shark's nostrils operate independently and guide it towards the direction of the strongest smell. 
When at close range, the shark is getting an increasing amount of messages into its skin organs. Lateral line starts to provide information about the possible stress in the water, pit organs are providing chemical details and finally its extraordinary eyesight gives it a visual image of the site. All of these sensations are evaluated in the brain, disciplined by 300 million years of genetic memory. 
It requires more than just a sighting of a human to raise a shark's appetite. Sharks don't always bite for hunger and if it happens that one decides to use its teeth on you, the game is not over yet. In 50-75% of shark attacks on humans, the shark only inflicts one bite without removing any flesh. Sharks like to investigate first and this accounts for many attabcks. Judging from survival rates, sharks don't have a taste for humans. Modern communications, effective transport and good first aid saves majority of victims. Those unlucky (around 10-20 per year) who don't survive will often die from the lack of efficient first aid rather than from being eaten.
What really goes on in a sharks mind, we don't know. Studying shark attacks reveals that in almost all cases there have been factors that confused the shark. The contributing factors on shark attacks could roughly be divided in three categories:
-Dead fish / blood in the water
-Turbulent / dirty water or poor visibility
-Provoking / interacting with sharks
In the first category the risk is pretty obvious. Knowing how sensitive sharks are for smells and vibrations, carrying wounded fish, spear fishing or swimming / diving near fishing boats, is asking for trouble in shark infested waters. The second category would include many investigative bites. Swimming in river mouths, or at dusk increases the risk of being subjected to close-range shark-curiosity. The third category is again common sense. If you want to burn yourself, go and play with fire!

How to minimise the risk?
We now know that sharks don't go hunting for humans, nor do they charge from the depths with their jaws open, to eat whatever comes their way. A whole lot of unfavourable conditions have to come together before the water around you turns red. The only way to completely eliminate the risk of shark attacks, is to never go in seawater. (Include Lake Nicaragua in that!) In the modern days of water sports, it can mean a pretty boring holiday, so let's look at some other means of minimising the risk. First of all, when you go to a location unfamiliar to you, ask the local tour guides or lifeguards about the safety in that area. There may not be any need for precautions. If, however sharks are clearly around, obey the following guidelines:
•	If scuba diving, go with a group, led by the local dive operator. They will not take any chances as their income depends on the safety of their customers. If you see sharks during your dive, enjoy the opportunity to observe this gracious predator. Don't provoke, feed or approach a shark, even a small one. 
•	Avoid wearing shiny objects or bright colours, particularly orange or yellow. 
•	Never go spear fishing in waters inhabited by sharks. It is equally dangerous for snorkellers and scuba divers, as the smell and vibrations of your catch will most likely attract sharks. Stay clear of any fishing activities when in water. 
•	Don't go far off the beach or swim beyond the surf. If you swim alone in open waters, your movements will stand out and make you a more interesting object for a passing shark (As I discovered myself in Timor Sea!). 
•	Don't swim at night or at dusk. Many sharks feed actively at night, when their extra sensitive eyesight gives them an advantage over their prey. 

So who's afraid of sharks? I'm not. At least no more than crossing the road. And just like with traffic, with sharks we only need some basic knowledge, common sense and adaptation to local conditions. We live in a dangerous world, but if you are not frantically worried about car crashes, house fires, electric shocks or falling meteorites, don't let the Hollywood image of a shark spoil your holiday. 

(c)Lauri Strengell 1996
!SHARKS.DOC	printed: 7/10/03

page