Interesting facts about sharks - are they attracted to human foods

Sure sharks eat seals, fish, dolphins, sea lions, and other underwater mammals and fish. But these types of foods certainly are not on our plates. So can they be tempted by other kids of meat? Like turkey? You know the kind that rests on our plate for thanksgiving break? You would guess yes right? I mean sharks are big gluttons, and if they are capable of taking big bites out of us then of course they’ll eat other meats, especially if it’s thrown out to them for free. I mean, they would be silly not to take it. Well, let’s find out.

Researchers have tested to see whether or not Sharks can be tempted by “our” kinds of meat. They head to the local grocery store and pick out a few cuts : whole turkey, ham, beef ribs They head out to the sea to conduct their tests. They first throw the turkey out to the sea, to the shark. It bites! But wait, it spites it right out! That’s right, it took a bite our for sure, but then spit it out, its not interested. Next on the list, ham. Good ol’ ham, will the shark reject it too? What’s this? It didn’t want the Ham at all, didn’t even take a bite. I guess it’s really not interested.

Well, now for the beef ribs, and its 50 pounds of beef ribs at that, let’s see if this is any different. Indeed! It took a bite, and a big one at that, it’s a keeper. The shark eats it all, its one well fed shark. So lets recap here, the shark is interested in the turkey, but not enough to eat it. The shark couldn’t care less about the ham, and the beef ribs, well lets just say there were none left. So what might this suggest? A big great shark like the great white may only be satisfied by large prey. Which means that for us humans, we may not have enough fat content to satisfy the shark, but we may just be big enough for him to become interested.

What are the various adaptations a shark has, and how do they help the shark search for prey?

Working with the precision of a finely tuned early warning system, each of the shark’s senses lock on as it approaches prey. With well developed inner ears, sharks can pick up sounds from up to 17 hundred yards away. Experiments have shown that sharks are particularly attracted to lower frequency sounds. Irregular vibrations with frequency at or below 40 hertz create frenzy among sharks. Not surprisingly this is the same frequency, made by a wounded fish.

As the shark closes within a few hundred yards of its eventual meal, the sense of smell takes over and guides it ever closer. A shark is capable of detecting a single molecule of blood in over a million molecules of water. The apparatus responsible for the smell is located in 2 nostrils near the front of the snout. As the shark swims, odor laded water is forced into its nostrils and over delicate sensory tissue. From about 100 yards, sharks are able to detect even the faintest vibrations created by the movements of struggling fish. At around thirty yards, the hunter can literally set its sights on the hunted.

The size and shape of shark eyes tends to depend on where the shark lives, sharks that feed in shallow waters usually have smaller eyes because they have more light to deal with, while sharks that live in deeper water have larger eyes. Some sharks also have an eyelid that closes to protect the shark while it bites its prey.

Shark teeth are varied in their design and purpose depending on the food source. The serrated and hooked teeth of a tiger shark are highly efficient sheering and tearing tools. Some teeth like that of the port Jackson shark are designed for crushing shellfish. The teeth of the Greenland shark are so sharp that they were once used by Eskimos for cutting hair. The wobegon uses its angled teeth to grasp its prey. Sharks lose teeth continuously throughout their lives. To replace them, some sharks have as many as 15 rows of teeth folded back into the tissue of the jaw.

What sharks choose to bite ranges from the predictable to the bizarre, one shark known to eat anything in its path is the tiger shark. Stomach contents have included things like : tennis shoes, medieval armor, nuts and bolts, tin can, life jacket, ammunition shell.

What are the odds of being attacked by a shark, and dying? We are about to find out. They are known as the terror of the deep. They have sinister eyes and powerful jaws with row after row of razor sharp teeth. Aided by popular movies and TV shows, the shark is enemy number 1 in the wild. But are these fears justified? What are the odds of actually being attacked by a shark this year and dying?

Not that they are looking for sympathy, but most shark attacks occur solely because they are hungry. You grab a burger at a fast food joint just like a shark has to hunt. Unfortunately a pair of legs may look like a couple of cod. The sharks generally have three ways in which they hunt. The first is the hit and run. It happens near beaches where the sharks lurk around looking for food. They mistake the human movement, usually near the surface, for regular fish. They then take one bite, which rarely causes death, and swim away.

The second is the sneak attack, which usually happens in deeper water. The victim usually does not see the shark before it strikes. It’s these attacks that are sometimes fatal. Finally there is the bump and bite. This happens when the shark circles its victim before attacking, it often takes more than one bite and strikes repeatedly. So what are the odds that you will be a victim to one of these attacks this year and die?

Contrary to popular belief, shark attacks are rare. On average about 33 Americans are attacked each year. So, your odds of being attacked are about one in 9 million. Less than one American each year is killed by a shark. So, your odds of being killed by a shark are about 1 in 400 million. Now, over half of all US shark attacks take place on the beaches of Florida. If you visit a Florida beach, then your odds of being attacked increase to 1 in 430,000, which is still quite rare. Your odds of being killed by a shark in Florida are about 1 in 36 million. So, it would seem as if going back to the water is safe after all.

Although sharks are boneless, they are still heavier than sea water and must swim to avoid sinking. Bony fish have air bladders to help make them buoyant. Sharks rely, instead, on enlarged livers. These livers are filled with as much as 18 gallons of an oil that is lighter than sea water. This along with their fins, gives them lift.

Sharks which range across the open seas have large livers compared with their body size. Bottom dwelling Sharks have smaller livers because they do not need to travel as far off the sea floor. The only shark that uses air for additional buoyancy is the sand shark which gulps air to allow it to hover. A swimming shark is very much like a well designed air craft in-flight. Coordinated movements of the dorsal and pectoral fins allow it to move smoothly. But because of their streamlining, sharks pectoral fins are less flexible and don’t rotate like those of a bony fish. Fish can reverse, and sharks can not.

Instead, the shark has to fall away from obstacles instead of just reversing. Sharks are infamous for their menacing front teeth. In actuality, little know that the sharks entire body is covered with teeth. How is that for a shock! They are called dermal-denticles or skin teeth. They are pointed backwards to smooth the flow of water over the body and reduce drag. This in turn helps to increase speed. It is however, the sharks tail that controls its speed, these tails are designed to suite the sharks way of life. Bottom dwelling sharks feed on slow moving prey, so their tails are designed to give them more stability rather than speed. In open water sharks the tails are designed for great burst of speed and power to catch fast moving prey.

One of the most powerful swimmers is the hammerhead. Located at each side of its anvil shaped head is an eye, a nostril, and sensory organs, which help them to steer, and to detect prey more easily.

Researchers attach satellite transmitters to the sharks in order to track them. They use a lance and mounted transmitter, get the shark close to the boat and then carefully place the tracker at the base of the dorsal. This is known as the dorsal saddle. From there, the shark caries the device and at a prearranged time, the burn wire on the device releases the transmitter which floats up to the top and becomes oriented straight up and down with the aerial in the air. At that time the satellite begins to interrogate the archival tag. It takes all of that information down to a land based computer where researchers can aces and analyze it.

While researchers tag the sharks in an effort to learn more about them, the actual process of tagging may turn out to be quite dangerous. While there are dangers and risks associated with tagging, the act is imperative for shark researches. By tagging and recapturing sharks, researchers can learn where they go, find out how long they live, and keep track of their reproduction and health. The current long distance record is held by a blue shark tagged off in New York and recaptured 3, 740 miles away off the South American Coast.

They may be successful predators, but sharks are vulnerable. Shark populations are declining all over the world. The populations are declining mainly due to over-fishing. They are used as a food item in many parts of the world, shark-fin soup is particularly popular in Asian countries. Sharks are also easy to catch, you put a baited hook in the water and if a shark is nearby it will bite the hook.

So they are easy to catch, easy to kill. Apart from the catching however, what works against them is their low reproduction rate. Sharks produce only a few pups, compared to fish who produce thousands. So when a shark is killed, its difficult to replace the missing sharks. The shark also has to be several years old before they are capable of reproducing.

Thus, world wide there is unfortunate decline in the numbers of sharks. This does not apply to all species. Of the hammerheads, the great hammerhead is most vulnerable to over fishing, and is currently endangered because of this. Without problems as such, the sharks thrive in their natural habitat: the open seas.

While some sharks seem to be disappearing, scientists are, surprisingly, still having their first encounters with some species of sharks. One shark that was recently discovered was the prehistoric Greenland shark. This shark puzzles researchers. Yet as researchers come to know this and other sharks better, they find that there are still more questions than answers. Researchers do know that sharks can be cunning, ferocious, and even comical. They certainly do not however, deserve their reputation for mindless evil. Sharks have been swimming the oceans for over 400 million years. They survived the extinction of dinosaurs and will probably be here long after we are gone. And so, sharks should be respected for the great creatures that they are.

Much like tropical fish today, these flying sharks probably traveled in schools. This is a good survival tactic for fish that might have grown only a foot and a half long. They were heavily armored creatures with huge eyes. These sharks had denticles, tooth like structures on the leading edge of their pectoral fins. When danger threatened, they escaped the jaws of larger predators on their wing like fins.

Three hundred million years ago, sharks were evolutionary innovators. They filled many more ecological niches than they do today. Each animal was stranger looking than the next. Back then, sharks were amazingly diverse, filling up about 60% of all fishes, compared with only 3% today. Shark researchers today attempt to find fossilized sharks, which is a matter of luck, even for those well experienced. They search for the missing links in shark evolution and the relatives of modern sharks, skates and rays.

The first sharks appeared in the oceans around 400 million years ago, but they bore little resemblance to the ones that inhabit the seas today. Edestus giganteus grew to a size as large as today’s great white and had a set of gigantic scissor like jaws. The helicoprion had teeth that were designed in a whirl and designed for crushing hard shells. A close relative of toddy’s great white, but twice its size, the megalodon was perhaps the largest of all predatory fish. It became extinct between 1 and 3 million years ago but is still regarded as a modern shark. Modern sharks began there rise to dominance late in the age of the dinosaurs , some 140 million years ago, at the same time another group branched off, evolving into the rays and skates of today. Some rays still look a bit like sharks, others don’t at all.

Sharks were obviously an evolutionary hit. Today any shark with more than five pairs of gills are thought to be a more ancient species.

Oceans cover more than 70% of the earths surface and hold more than 20,000 species of fish, of these some 370 species are sharks. Long before dinosaurs existed, sharks roamed the waters. They first originated more than 400 million years ago and have changed very little in the last 100 million years. Today, few other species on earth inspire so much respect and fear. These amazing predators sit atop the marine food chain. By weeding out the week and injured they help maintain a balanced ecosystem.

Sharks are highly tuned hunting machines that rely on their specialized senses to catch prey. Using their sharp sense of hearing they can detect sound vibrations up to 3,000 feet away. They are especially sensitive to the low frequency pulses from struggling prey. As a shark gets closer to the catch, its sense of smell takes over. It can detect a single drop of blood in 25 gallons of water. Water flows through nostrils on the underside of its snout, which gives the shark a steady stream of olfactory information. Near the snout, sharks also have tiny jelly filled pores, which pick up electrical signals created by moving animals. This is like an extra sense that helps sharks find prey, even if it’s hiding under the sand.

When we think of sharks, we can’t help but think of their teeth. Sharks use and lose their teeth all of the time. Some species shed as many as 30,000 during their lifetime, but replacements are always nearby. But rows of teeth make it possible to rotate in new teeth when needed. Besides their reputation, one thing that distinguishes sharks from other fish is their skeleton, which is made of tough, flexible cartilage instead of bone. Cartilage is lighter than bone, so the shark uses less energy as it swims, than a bony fish does. Tough skin covers its streamlined body, tiny teeth- like structures make the skin as rough as sand paper, making the skin as rough as sand paper and protect the shark from injury. These teeth point backward to reduce the drag from the water, as the shark races through it. So many advantages make sharks one of the most efficient predators on earth!

We haven’t always been this fearful of sharks. There was a time just after the turn of the twentieth century when most swimmers hardly gave a second thought when they went swimming. Some scientist argued whether sharks were even strong enough to bite through human bone, much less kill someone. But in 1916 it all changed with a series of attacks off the coast of New Jersey. July 1916 was the first shark attack in American history, that is, recorded human history. Attacks were really not highly known until these highly publicized series of incredible attacks in New Jersey in 1916.

That saga began July 1, 1916 when Charles Vansant was attacked by a shark in Beach haven in Southern New Jersey. Only five days later, July 6, Charles Bruder, was attacked and killed off the coast of Spring lake New Jersey. He was nearly bitten in half in front of a beach crowded with people. A few days later, possibly the same shark swam up the Matawan Creek just south of New York City, Maimed one swimmer and killed two more. This was a headlined grabber, possibly just like that of the attacks that occurred in the summer of 2001, which time magazine named the summer of the shark. The media went crazy.
Reports of the shark attack pushed aside reports from World War I, replacing them with tabloid style exclamations about the sea wolves threatening swimmers lives. A massive hunt for the killer ensued up and down the Jersey Coast and in the creek itself. Two days after the attacks in Matawan creek, a nine foot great white shark was captured off the coast of south Amboy New Jersey. Fifteen pounds of human flesh and bones were found in its belly. No further attacks were reported and beaches soon returned to normal. But the seed of caution had been planted, the threat of sharks had become real in the minds of many.

Throughout the 50’s 60’s and early 70’s , sharks pretty much stayed out of the headlines, that is until 1974 when Peter Benchley’s novel Jaws was published. Suddenly, there was a reason to fear the surf again, even if it was fiction. A year later the movie came out, forever altering our perception of the shark threat.

They are known as ruthless hunters and vicious killers, creatures so deadly that human encounters only seem possible within some sort of protective casing. 30 species of sharks have been known to attack humans so it’s not so difficult to understand why humans respond to sharks with a mixture of fear and admiration. But fear is not what stops us from learning more about sharks. Many species live secrete lives in some of the remotest corners of the oceans. Sharks remain among the great mysteries of the natural world.

About 30% of shark species are born from a fertilized egg sack which is deposited on the ocean floor in a strong leathery casing which gives shelter to the growing embryo. Some sharks like the hammerhead give birth to live young like humans. Some sharks have eggs that develop inside the mother’s body and then hatch. Some sharks make there home on the sea floor, while others make their homes on the upper regions. All of them are crucial in maintaining the delicate balance of the ocean ecosystem by continually weeding out weaker or injured creatures. A growing understanding of today’s present sharks gives us some information of past sharks. With little evidence preserved from their boneless ancestors, today’s sharks are studied as living fossils, adding bits and pieces to the story of how sharks evolved.

There are various types of sharks, and they are all unique. Among the sharks that live in shallow water, the southern catshark is an evolutionary oddity. It glides through the water with sinuous movements that are more reminiscent of a snake than a shark. Even stranger is the epaulette sharks which uses its fins in an action that is unique among sharks, to walk along the sea floor. Some sharks like the Wobbegongs have evolved body patterns that act as a convincing disguise. Its also referred to as the swimming carpet, the Wobbegong blends into the kelp beds where it lives. The tiger shark, a fierce hunter, has body patterns that mimic the ripples of the ocean water.