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1.       All sharks are man-eaters with massive teeth

        Not all sharks are large, bulky, and torpedo-shaped like the ones we see in movies. There are nearly 400 different species of shark and they are significantly diverse in terms of size, habitat, behavior, diet, and morphology. Not all sharks have a mouth full of large pointed teeth for tearing flesh. The basking shark has tiny teeth that it doesn’t even use for feeding, and the horn shark also has molar-like teeth that it uses to crush hard-shelled prey. Sharks have evolved a variety of teeth shapes in order to best suite their targeted prey. Sharks range from about 6 inches long, like the cigar shark species; up to about 45 feet long like the whale shark. More than 50% of sharks are 3 feet long or less; more than 80% are under 5 feet. Of the 400 different shark species, only 3 have been involved in a significant number of human fatalities.


2.       Shark attacks are common

        Your chances of being attacked by a shark are very slim, even if you are involved in water activities (like surfing and diving). To put it into perspective, people are 250 times more likely to be killed by lightning than by a shark. That is not to say unprovoked bites don’t happen, there are about 70-80 reported each year, but these are usually out of curiosity and are rarely fatal. Within the period of 1999-2009 an average of fewer than 5 people died from shark attacks in the world. When you consider the millions of people involved in water activities during that period, you will realize that shark attacks are not as common as they are made out to be. You are 10 times more likely to be bitten BY A HUMAN in New York City than you are bitten by a shark worldwide! Even falling coconuts kill 150 people across the world each year. You are more likely to be killed by a dog or a falling vending machine than you are a shark. Yet, I never see people shudder in fear as they approach a machine for their bag of chips.

3.       Sharks Can Detect a Single Drop of Blood in the Ocean!

        Sharks are often portrayed as having an almost supernatural sense of smell. However, reports that sharks can smell a single drop of blood in a vast ocean are greatly exaggerated. While some sharks can detect blood at one part per million, that hardly qualifies as the entire ocean. Sharks do, however, have an acute sense of smell and a sensitive olfactory system - much more so than humans. Sharks' nostrils are located on the underside of the snout, and unlike human nostrils, are used solely for smelling and not for breathing. They are lined with specialized cells that comprise the olfactory epithelium. Water flows into the nostrils and dissolved chemicals come into contact with tissue, exciting receptors in the cells. These signals are then transmitted to the brain and are interpreted as smells.

        Because of the extreme sensitivity of these cells, as well as the fact that the olfactory bulb of the brain is enlarged, sharks can detect miniscule amounts of certain chemicals. This varies, of course, among different species of sharks and the chemical in question. The lemon shark can detect tuna oil at one part per 25 million - that's equivalent to about 10 drops in an average-sized home swimming pool. Other types of sharks can detect their prey at one part per 10 billion; that's one drop in an Olympic-sized swimming pool! Some sharks can detect these low concentrations of chemicals at prodigious distances - up to several hundred meters (the length of several football fields)—depending on a number of factors, particularly the speed and direction of the water current.

        Predation is not the only behavior in which olfaction plays a crucial role. Evidence exists that this keen sense of smell is also instrumental in sexual behavior. Males are able to detect pheromones produced by females, even in low concentrations, helping them locate potential mates.

4.       Sharks can’t see well and often mistake surfers & divers in wetsuits for prey

        A shark’s most well-known sense is definitely their smell but they also have an excellent visual system as well. Behind a shark’s retina is a reflective layer called the tapetum that magnifies light signals for night-active sharks that live in the deep. Scientists believe that sharks can see as well below the surface, as humans do above it. Great whites are one species of shark that are very sharp sighted. They can even see in color. It is unlikely that a shark would mistake a human for prey. Sharks are curious and investigative animals. What people don’t realize is that when a shark is unsure about what something is, it takes a bite in order to investigate. Whether that unfamiliar object is a person or a crab pot, they are looking for tactile evidence about what it is.

        Think about it, if you observe a great white attacking a seal as compared to when they bite a human or an unfamiliar object, it further proves the point. When attacking what it thinks is prey, studies have shown that a great white would likely rocket to the surface from depths and pulverize their prey with incredible force. On the other hand, these sharks usually approach humans and other objects with leisurely or undramatic behavior. It takes a lot of energy expenditure to hunt in this fashion so a shark would not waste this energy unless it was attacking prey. This shows it is unlikely that a shark would mistake humans or other objects as prey. What’s more likely is that the shark’s action was not predation but merely curiosity.  

5.       Sharks aren’t important. Who cares if they are all killed?

In The Ecosystem

        As apex predators, sharks play an important role in the ecosystem by maintaining the species below them in the food chain and serving as an indicator for ocean health. They help remove the weak and the sick as well as keeping the balance with competitors helping to ensure species diversity. As predators, they shift their prey’s spatial habitat, which alters the feeding strategy and diets of other species. Through the spatial controls and abundance, sharks indirectly maintain the seagrass and corals reef habitats. The loss of sharks has led to the decline in coral reefs, seagrass beds and the loss of commercial fisheries. By taking sharks out of the coral reef ecosystem, the larger predatory fish, such as groupers, increase in abundance and feed on the herbivores. With less herbivores, macroalgae expands and coral can no longer compete, shifting the ecosystem to one of algae dominance, affecting the survival of the reef system.

In The Economy

        Sharks’ control over species below them in the food chain indirectly affects the economy. A study in North Carolina showed that the loss of the great sharks increased the ray populations below them. As a result, the hungry rays ate all the bay scallops, forcing the fishery to close. Without scallops to eat, the rays have moved on to other bivalves. The decline of the quahog, a key ingredient in clam chowder, is forcing many restaurants to remove this American classic from their menus. The disappearance of scallops and clams demonstrates that the elimination of sharks can cause harm to the economy in addition to ecosystems. Sharks are also influencing the economy through ecotourism. In the Bahamas, a single live reef shark is worth $250,000 as a result of dive tourism versus a one time value of $50 when caught by a fisherman. One whale shark in Belize can bring in $2 million over its lifetime.

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6.       We should fear sharks

        In the past, sharks have killed worldwide: in 2005:4 people; 2006: 4 people; 2007: 1 person; 2008: 4 people. With these statistics, they are labeled as the most feared and biggest predators of our Oceans. On the flip side, humans kill an estimated 73 million sharks a year, mainly through fishing. That translates to more than 8,333 killed every hour! As many as 100,000 sharks die as a result of bycatch every year. Shark finning, however, is the cruelest practice that kills millions of sharks a year. So are we really the victims here? Or is it safe to say sharks aren’t the fiercest predators of the seas, but it's us humans? I'll let you decide.  

- Chris L.                                                                                                                                              


 


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