Wednesday, April 23, 2008

Great White Shark

The Great White Shark

The most fearsome hunter in the ocean has no skeleton. Its ancestors dined on dinosaurs. It sometimes eat people. It's the great white shark.



www.elasmodiver.com

Facts about Great White Shark( black tipped pectoral fins.

Length: Most reach an avarage length of 10 to 12 feet (6 meters).

Weight: Most weight about 1000 pounds (450 kilograms), but some may weight as much as 2 tons (1800 kilograms).

Color: Dark grey on top and off-white on the bottom.

Distinctive Habits: Hunts along shorelines for mammals. Although it is thought to eat people, few cases have been reported.

Food: Fish, squid, seals, sea lions, whales.

Reproduction: Eggs hatch in female's body. Then female gives birth to live offspring.

Life Span: Unknown.


Works Cited
Markle, Sandra. Great White Sharks. San Francisco: n.p., 2004. 
Martin, James. The Great White Shark. N.p.: Capstone Press, 1995. 
 

Sunday, April 20, 2008

Picture Gallery


































































Works Cited:


Great White Shark. 10 Mar. 2008 http://www.elasmodiver.com.


Great White Sharks Pictures. 12 Mar. 2008 http://www.apexpredators.com/‌store/.


National Geographic. 12 Mar. 2008 http://ngcblog.nationalgeographic.com/.


Shark Research Institute. 12 Mar. 2008 http://www.sharks.org/.


Sharks. 11 Mar. 2008 http://www.reefnews.com.


Sharks Find Out Now. 9 Mar. 2008 http://sharks.findoutnow.org.


Shark Species. 2 Mar. 2008 http://newenglandsharks.com.


Sharks Pictures. 12 Mar. 2008 http://www.elasmodiver.com/‌sharkive%20index.htm - 103k .


Zoom Sharks. 10 Apr. 2008 http://www.enchantedlearning.com/‌subjects/‌sharks/.



http://video.google.com/videoplay?docid=8964414149458454494&q=sharks+videos&ei=nSYMSKOXMYSE4gLbypW1BA&hl=en

http://www.youtube.com/watch?v=2nrA7-bGu7o&feature=related

http://www.youtube.com/watch?v=xWEdStaaZyE

http://www.youtube.com/watch?v=afpThH8NUxs

http://www.youtube.com/watch?v=mneDhOtVEQw&feature=related

http://www.youtube.com/watch?v=qHnS8_0da6A

http://www.youtube.com/watch?v=gOn9qeTXJ1k&feature=related

http://www.youtube.com/watch?v=fGf_LGX0594&feature=related

Shark Attacks

www.sharkattacks.com



Great White shark attack photo gallery of an attack in Aldinga Beach Australia (1963). Victim required 462 stiches.
Rod Fox, Aldinga Beach, South Australia

In 1963, Rodney was in a spearfishing contest in Australia.
He swam down to spear a fish but felt something was wrong straight away. Before he could react he was hit by a large Great White shark.
He was quickly rescued by a boat. His injuries were horrific.He had 462 stitches.

His wetsuit iscredited with holding him together. One lung was punctured. His ribs were exposed and bone was showing along his right hand and arm. The shark was estimated to be about nine foot long.




www.sharkattacks.com



Dawn Schauman of Melbourne Beach, FloridaDawn was attacked by a 10 foot bull shark, while she was 6 ½ months pregnant. The attack was on October 26, 1993, around 10:00 a.m.


References:

Shark Attacks. 11 Apr. 2008 . 





PRECONCEIVED IDEAS
Certain falsehoods concerning Sharks

Hunger does not exist in sharks. This is untrue. "The shark is capable of very long periods of fasting, and it seems that it may have periodicity in its eating habits. During these "eating phases" it is evident that we can talk of "hunger", and attacks then will be different in their determination and development." (Reader's Digest 91)

The shark have a very poor eyesight. Not only can a shark see contrasts well, but it has good night vision thanks to a histological structure peculiar to nocturnal animals. It can even see colors.

Sharks attack in order to feed. The image of the insatiable shark that swallows everything it encounters in order to assuage a hunger that is never satisfied is one of the most false. Over 1500 cases of shark attacks on on men ,50-75% of these attacks have nothing to do with nutrition.


Works Cited

Compagno, Leonard, Marc Dando, and Sarah Fowler. Sharks of the World. N.p.: n.p., n.d. 
Digest, Reader's. Sharks. New York: n.p., 1998. 
Books Recommended About Sharks:





Shark: The Shadow Below





Shark!






Great White Shark!







Sharks! : Predators of the Sea









Sharks and Rays







Best Book of Sharks








Encyclopedia of Sharks









Sharks









Shadows in The Sea; The Sharks, Skates and Rays, Fully








Sharks







Sharks; The Perfect Predators





Great White Sharks

Fake Pic

www.hoax-slayer.com

The photo above was a classic email hoax circa 2002; it was claimed to be National Geographic's "Photo of The Year". What most people don't know is that the picture is fake! It was spliced together from a U.S. Air Force photo taken near San Francisco's Golden Gate Bridge (as we can see) and a photo of a Great White Shark from South Africa.
PS: There has not been a "great" white shark sited in the San Francisco Bay since the 1960s.



www.hoax-slayer.com

References:

Shark Information. 28 Mar. 2008 . 




The Truth Beyond The Myths About Sharks

If you ask someone who had watched JAWS what was the impact the movie had on them, they will probably say it was not positive at all. Most people have misconceptions about sharks. The movie made people face sharks as horrible creatures and after the movie came out these people began to fear swimming in the sea. The media likes to sensationalize things. The idea of a big fish, full of acute teeth that are mostly like razors swimming in our beaches caused horror among people. This fear increased among many people that suffer from phobia of sharks. "This phobia is most known as Selachophobia - which is the scientific name for an abnormal and persistent fear of sharks - is a serious problem for many would-be swimmers." (Reader's Digest 25) Sufferers are usually completely unable to swim in the sea, even when reassured that shark nets other safety procedures are in force. "After the movie "Jaws" was released in 1975, the occurrence of Selachophobia had increased a lot. Some scientists argued that "Jaws" has been indirectly responsible for the wide-scale and irresponsible slaughter of sharks all over the world since 1975. It has contributed to the decline of great white populations as a result." (Compagno 27).

Until the beginning of the XX century, sharks were barely known among the public; swimming in the ocean was considered a quaint habit in the occident countries and just a few people had really seen a shark alive. "Myths related to sharks have played an important part among many cultures all around the world for many centuries. A jar founded in Italy, dated around 725 b.C., illustrates a man being swallowed by a big fish, and this was the first known occidental representation of a shark attack." (Macquitty 36). From that time on, there had been many artistic and literary descriptions of shark's attacks. Some brain trusts believe that the biblical story of Jonas was based originally on a great white shark, instead of a whale.

Is the movie "Jaws" responsible for all that scare? There is no denying that all general fear of sharks is a recent phenomenon and that it had increased a lot with the launching of Spielberg's movie, in 1975. "The clashing descriptions of the attacks and John William's memorable conquest initiated a lot of hysteria among people and the destruction of sharks all around the world." (Llewellyn 57). Sharks have also gotten a hard time for news reports. Whenever there is a shark attack, it is front page news, and it is always on the news channel. The worst part is that sharks are always shown as villains by the media. But people should be able to see that many sharks are fished and killed by humans. So who is actually the predator and who is the prey? "While the number of shark attacks is relatively rare, around 70 and 90 attacks per year in which most of the victims survive, the number of sharks being exterminated goes from 100 to 150 million per year." (Llewellyn 58).

The stories became alive for millions of people all around the world after the movie "Jaws" came out reminding people that there are many terrifying creatures hidden in our oceans. Different from the classical horror movies, in which the big impact is based on our imagination, "Jaws" was based in reality. Although the fish that terrified Amity's Island had never existed, the 5, 18 m and 2,035kg great white shark which had inspired Peter's Bencheley original story certainly existed. A row of fatal attacks in New Jersey in 1916 definitely happened; and by that time there was no massive covering media as we have nowadays. "Like the USS Indianopolis shipwreck in 1945 - a memorable event described by the character Quint on the first "Jaws" movie - , that resulted in hundreds of American sailor's deaths related to sharks attacks." (Macquitty 33).

It would not be a surprise that some people who had watched the movie had negative reactions related to the movie "Jaws". Although mane evidences prove that shark attacks are very rare - a person is more likely to be hit by a lightning than killed by a shark -, the fear still exists. It's a phenomenon that many psychologists and marine biologists relate to the book "Jaws" and Spielberg's movie "Jaws" which was based on the book. It seems like some people just cannot separate fiction from reality. "Nowadays, a few fatality rates result in revenge against these animals; and the shark phobia is still a serious problem for many people, even for those who live near the coast." (Stevens 12).

Scientists have been studying sharks trough the past years to get to know shark's behavior better in order to understand why do they sometimes attack people. In fact, sharks do not have a good sight. They can see colors but their sight is not good enough to distinguish for example a surfer from a seal or a turtle. "Sometimes they confuse humans with big fishes, turtles, seals, and other animals that take part in their diet. They do not attack humans for the sole purpose of hunger. In reality, sharks can go for many months without eating so they do not attack because they are hungry." (Stevens 86). This is not to say that sharks do not attack with the intention of seeking prey. Many attacks to humans (divers or surfers) can be connected to the search for food. "To a shark, a surfer on a surfboard slightly resembles that of a seal or a sea lion, or a diver in a black wetsuit can look like other prey" (Stevens 87).

When sharks feel that they are being provoked or when they are agitated by a person they can also attack on defense. "Many spear-fishers have been attacked by reef sharks because when they spear fish, the blood from the fish and its vibration can attract sharks." (Thomson 41).

There is no specific rule to avoid a shark attack. Even nowadays with all the technology available and all the studies on sharks' behavior, a shark attack is still unpredictable. But there are some directions which can be followed in order to decrease the already small chance of becoming a victim of a shark attack. First, a person should always swim in a group (sharks most often attack alone individuals). Another important thing is to avoid the water at night, dawn, or dusk. Many sharks are most active at these times and better able to find you than you are to see them; don't enter the water if bleeding; sharks can smell and taste blood, and trace it back to its source; don't wear shiny jewelry because the reflected light looks like shinning fish scales and avoid going into waters containing sewage. Sewage attracts bait fishes, which in turn attract sharks. Try to avoid the most to swim in waters being fished and those with lots of bait fishes. Diving seabirds are good indicators of such activities; don't enter the water if sharks are present. Leave immediately if sharks are seen; avoid uneven tan and brightly colored clothing. Sharks see contrast particularly well, so use extra caution when waters are cloudy; don't relax just because porpoises are nearby. Sightings of porpoises do not indicate the absence of sharks. Both often eat the same foods. (May 10).

People should try to read and get more information about sharks instead of accepting what the media tell them without questioning. "The extinction of sharks, due to man fishing for, or hunting sharks, and even man polluting the oceans is a reality" (Reader's Digest 92). Sharks are disappearing from the world's oceans. "Research groups estimate that some species of sharks have declined 80% in population in the last ten years. It is also estimates that a few species of sharks will be extinct within the next ten years" (Stevens 51). In order to fight against shark's extinction, people should get involved into some groups of shark's preservation and combat predatory fishing of those animals. Also the media takes advantage on the fact that people fear the unknown and that they love to listen to scary myths and things like that. The media should be more realistic and fight for shark preservation instead of referring to them as viscous and bloodthirsty animals. If the media continues to show Sharks as if they were monsters, people are going to feel in the right to fish them and continue the extermination process.


Tips to Avoid Shark Attack


Always go into the water in groups as sharks prefer lone prays



Do not enter the water if you are bleeding. sharks can smell and taste blood, and trace it back to its source;



Avoid swimming at dawning or sunset, when sharks are most active.




Don't go into the water at night, dawn, or dusk.




Don't wear shiny jewelry because the reflected light looks like shinning fish scales.




Avoid going into waters containing sewage. Sewage attracts bait fishes, which in turn attract sharks.




Try to avoid the most to swim in waters being fished and those with lots of bait fishes. Diving seabirds are good indicators of such activities;




don't enter the water if sharks are present. Leave immediately if sharks are seen;




avoid uneven tan and brightly colored clothing. Sharks see contrast particularly well, so use extra caution when waters are cloudy;




don't relax just because porpoises are nearby. Sightings of porpoises do not indicate the absence of sharks.




Both often eat the same foods.


Don't wander too far from shore. Doing so isolates you and places you away from assistance.


Don't try to touch a shark if you see one!

If attacked by a shark, the general rule is "Do whatever it takes to get away!" Some people have successfully chosen to be aggressive, others passive. Some yelled underwater, others blew bubbles. I personally would go down fighting.

When visiting a new area, seek local advice.

Always heed current shark warnings.

Avoid Swimming with an open wound; sharks may be attracted to blood and bodily fluids.

When spearfishing, be careful! Avoid filing the water with blood.

Learn to recognize when a shark is feeling threatened by your presence.

Avoid areas where people are fishing.





SHARKS UNDER ATTACK


Although sharks rarely kill humans, humans are killing about 20 to 30 million sharks per year through commercial and sport fishing.


Sharks are blessed with outstanding senses of smell, taste, hearing, and sight; the ability to detect minute changes in water pressure and electromagnetic fields; and other attributes that make them nearly invincible in the sea. Yet they are quite vulnerable to a baited hook and are easily caught. In many areas of the world sharks are becoming seriously overfished and some species are seriously threatened.More and more people understand that sharks are a valuable part of the ocean environment and must be protected. Fishery management plans have been developed in many areas, but similar action is needed in many other regions. Certain species, such as the white, sand tiger, whale, and basking sharks, have received special governmental protection in some countries.


Works Cited

Carwardine, Mark. Shark. London: n.p., 2004. 
Digest, Reader's. Sharks. New York: n.p., 1998. 
Llewellyn, Claire. The Best Book of sharks. N.p.: Larousse Kingfisher Chambers, n.d. 
National Geographic. 10 Mar. 2008 . 

Saturday, April 19, 2008

INTERESTING FACTS:

Sharks have the most powerful jaws on the planet. Unlike most animals' jaws, both the sharks' upper and lower jaws move.
A shark bites with it's lower jaw first and then its upper. It tosses its head back and forth to tear loose a piece of meat which it swallows whole.

Each type of shark has a different shaped tooth depending on their diet
Sharks never run out of teeth. If one is lost, another spins forward from the rows and rows of backup teeth.

Normally, sharks eat alone. But sometimes one feeding shark attracts others. They swim up as quickly as possible and all begin to try to get a piece of the prey. They bite wildly at anything that gets in their way -- even each other.
The great white shark rarely partakes in feeding frenzies.

Almost all sharks are "carnivores" or meat eaters. They live on a diet of fish and sea mammals (like dolphins and seals) and even such prey as turtles and seagulls.
"Sharks even eat other sharks. For example, a tiger shark might eat a bull shark, a bull shark might eat a blacktip shark and a blacktip shark might eat a dogfish shark.
The teeth of the carnivores are sharp and pointy. Their skeleton is made of cartilage instead of bone, which allows greater flexibility." (Martin 10)

"Their skin is made of denticles instead of ordinary fish scales. The denticles are constructed like hard, sharp teeth and help to protect the shark from injury." (Martin 15)

Not all sharks are fierce carnivores. Some are quite harmless. Oddly enough, the most harmless sharks tend to be the largest! The basking shark, the whale shark and the megamouth sharks all fit this description.

These huge sharks eat plankton, a tiny shrimp-like creature found in the ocean. To do this, they swim forward with their mouths wide open. "Gill rakers" at the back of their throat strain the tiny food from the water.

Baby sharks are called pups. Just like there are many types of sharks, there are also different ways that sharks come into this world. There are three ways that sharks are born:

eggs are laid (like birds)
eggs hatch inside the mother and then are born
pups sharks grow inside the mother (like humans)

Sharks can have from 1 to 100 babies at a time, depending on the type of shark. The ones with pups that grow inside the mother have fewer babies at a time than sharks that lay eggs outside the body.

Sharks do not care for their babies after they are born, but they do search for a safe place where they can lay their eggs or give birth.

Sharks and rays do not have true bones like other fishes. They have cartilage instead which is lighter and much more elastic and allows them to bend in very tight circles.

Sharks have an extra sense that is able to detect tiny electric fields. They can use this to find food that is buried or search for animals to eat in the dark or in turbid water.


Works Cited

Digest, Reader's. Sharks. New York: n.p., 1998. 
Haven, Kendall. Wonders of the Sea. Monterey, CA: Challengers, 2005. 
Live Science. 4 Apr. 2008 . 
Shark Trust. 4 Apr. 2008 . 
One of the reasons that sharks are such successful predators is that they have such super senses.

"Two-thirds of a shark's brain is dedicated to its keenest sense -- smell." (Martinez 67).

Some sharks have eyes similar to a cat. A mirror-like layer in their eyes allows them to see better in the water. This allows the shark to hunt in clear seas or murky water.

"To top it off, sharks have a few unusual senses. For instance, they are able to feel vibrations in the water using a line of canals that go from its head to its tail. Called a "lateral line", these canals are filled with water and contain sensory cells with hairs growing out of them. These hairs move when the water vibrates and alerts the shark to potential prey. " (Parker 68).

Sharks also have a sensory organ called the "ampullae of Lorenzini" which they use to "feel" the electrical field coming from its prey.


Shark Facts:

"Sharks have been around for about 400 million years - long before dinosaurs even existed."

"Sharks have the most powerful jaws on the planet."

"Sharks never run out of teeth - when one is lost another spins forward from the rows of backup teeth."

"A shark may use over 20,000 teeth during its life."

"The Great White Shark rarely partakes in feeding frenzies."


Works Cited

Klimley, A. Peter. The Secret Life of Sharks. N.p.: n.p., 2003. 
Parker, Steve, and Jane Parker. The Encyclopedia of Sharks. N.p.: n.p., 2002. 
Shark Information. 5 Mar. 2008 . 
Sharks. 27 Feb. 2008 . 

Scientific Classification

SCIENTIFIC CLASSIFICATION:

  • Kingdom: Animalia
  • Phylum: Chordata
  • Subphylum: Vertebrata
  • Class: Chondrichthyes
  • Subclass: Elasmobranchii
  • Superorder: Selachimorpha


SHARKS SENSES:

One of the reasons that sharks are such successful predators is that they have such super senses.

Two-thirds of a shark's brain is dedicated to its keenest sense - smell.

"Some sharks have eyes similar to a cat. A mirror-like layer in their eyes allows them to see better in the water. This allows the shark to hunt in clear seas or murky water."

To top it off, sharks have a few unusual senses. For instance, they are able to feel vibrations in the water using a line of canals that go from its head to its tail. Called a "lateral line", these canals are filled with water and contain sensory cells with hairs growing out of them. These hairs move when the water vibrates and alerts the shark to potential prey.

Sharks also have a sensory organ called the "ampullae of Lorenzini" which they use to "feel" the electrical field coming from its prey.

Works Cited

Llewellyn, Claire. The Best Book of Sharks. N.p.: Larousse Kingfisher Chambers, n.d. 
Stevens, John Donald. Sharks. N.p.: n.p., 1999. 
INTERVIEW WITH ALYCE TODD, MARINE BIOLOGIST

Why did you decide to work with sharks?

Most aquariums exhibit sharks, so that is one of the reasons I started working around them. I really didn’t begin to appreciate them until after working around them.

What formal training did you get for this profession?

See the attachments. I have attached the pre-completed interviews of myself, one of the Aquarists, who works directly with the sharks, and a Trainer.

What do you think is the most fascinating thing about sharks?

For me, it is how their teeth work and that whole system. My favorite shark fact is that one shark can go through 30,000 teeth in a life time.

Why do they attack people?
Simply put… misidentification. The sharks think the people are food and bite them.

What should people do to avoid a shark attack?

Not go in the water when they see a shark or are told there are sharks near the area. Swim during the times when sharks are not active.

Do you agree with the image that the media shows to people about sharks? Why? Why not?

No. The media likes to sensationalize things. People want to hear the gory, scary parts of animal life (not just sharks, trust me). The only reports you hear about are the attacks or stuff like that.

Do sharks sleep?

Not like we do… they basically rest the parts of their brain that don’t control breathing.

Why do they dive alone and not in groups?

Most sharks are solitary because then there is no competition for food.

What was the closest/scariest encounter you have ever had with sharks?

Me, none. The sharks that we have here are used to people. I also know enough to not put myself in danger.

How do you use your work to educate people about sharks and the marine environment?

With the guests seeing the animals and how they behave, it really does dissolve a lot of the myths that they are machines. We also have divers that go in the exhibits with the sharks, so that helps.

What have you found to be among the biggest misconceptions people have about sharks?

They are machines that attack for the fun of it. Not true. The will eat when they are hungry. Attacking for the pure “fun” of it isn’t what they do. Also, that all sharks need to swim all the time in order to breathe… untrue. Only about 100 of the 350 species of sharks have to swim all the time; the rest have muscles over the gill slits to help pump the water. A stopped shark is not a dead shark.

Is the myth about punching a shark in the nose to scare it off true?

Not the “nose” (which is actually the rostrum), but he gill slits. It’s like us getting hit in the gut and having the wind knocked out of us.

Why do you think people are so fascinated with sharks?

They are mysterious, not much is really known about them. They are big and beautiful.

Have you seen a change to shark populations and distribution in your career? In what way?

Not really. There are a lot of laws protecting marine environments. There are not a lot of shark species on the endangered species list. They are [protected because the habitats they live in are protected.

Can you describe your first encounter with sharks?

My first wild encounter was when I was snorkeling in Australia and a small black-tip swam by. I took a ton of pictures, but then it dawned on me that there was no acrylic between me and it. I am so used to seeing the animals that being in their “house” was a bit of a reality check.

Have you heard anything about the relationship between sharks and cancer?

Yes. There are a lot of studies going on about the type of immune system sharks have and how they don’t get major types of illnesses. No conclusions yet, that I have read.

What kind of diet, and reproduction system do sharks have? Are they like humans?

Their stomachs are spiraled inside, so they can efficiently digest the food is such a small space. Some sharks reproduce via laying eggs, so they have the system of making egg pouches; some reproduce via live birth so they have a uterus and the babies are attached the to yolk sac in the uterus; then there is the type where they are in an egg case inside, develop and hatch out, then are birthed out the cloaca.

How do sharks attack? Do they have only one way of attack or is it different each time?

The will come from below and behind their prey to “sneak” up on them. They take one big bite to let the prey bleed to death or go into shock. Then they come back and eat. That is the basic formula and pretty much stays the same.

Is it true that some people have been attacked because they were wearing something bright?

That is myth. Scientists believe it is the behavior of the human, not what they were wearing. The bright clothes might contribute to flashes of light that their prey items make.

After getting attacked by a great white, how did you eventually go back to diving?

Not ever being attacked, I don’t know, but they do say that the best way to get over fear is to face it.

Your profession is extremely competitive. What advice do you give to aspirants who want to do what you do?

Get lots of experience working with animals. The most important thing is you understand animal behavior, so you can keep yourself safe, and the animals safe.



WHAT IS A SHARK?

All sharks belong to the class of fish called Chondrichthyes, which unlike bony fish have skeletons made of cartilage. Sharks do not have scales like bony fish but instead have rough skin. Their skin is covered with tiny sharp teeth called dermal denticles. These teeth can scrap the skin off your hand if you rub it the wrong way, which is from tail to head. When rubbed from head to tail sharks feel smooth (with the exception of a few species). The denticles are there to make the shark move silently, and protection. Another thing that separates sharks from bony fish is that their backbone extends into the upper lobe of the caudal fin. The shark also fertilizes internally, and has fewer young then bony fish. Reproduction will be in a different section.







1.Liver
2.Spiral valve
3.Heart
4.Pancreas
5.Stomach
6.Eye
7.Nostril
8.Ampullae of Lorenzini
9.Teeth
10.Pectoral Fin
11.Pelvic Fin
12.Anal Fin
13.Caudal or Tail Fin
14.Second Dorsal Fin
15.First Dorsal Fin
16.Gills

Sharks have highly sensitive senses, a special liver which helps them to float, several rows of teeth, and eyes which aren't so different from humans' teeth.
Like rays, shark skeletons are made of cartilage.
A shark has several pairs of gills on either side of its head, unlike other fish who only have one gill on each side. You probably breathe through your nose and mouth, but a shark only uses its nostrils for smelling. When people don't want to be seen by their enemies they sometimes wear fatigue suits. Sharks are born with their own special colors to protect them from predators above and below them in the water.

SHAPE:

The shape of a shark is specially designed to help it navigate long distances and maneuver around its prey with ease.
"When engineers came up with the shape of a DC-9 airplane, they were thinking about the fastest way to travel using the least amount of energy. If you compare the DC-9 to a shark, you will see that their shapes are amazingly similar. They both have round bodies tapering off at both ends. This shape allows the plane to glide through the air, and the shark to glide through the water, without using up all their fuel before they get where they want to go." (Stephens 32).

SKELETON:

The bones of a fish are made mostly of calcium, but a shark doesn't really have any bones. A shark skeleton is made of cartilage. Bony fish have a gas-filled swim bladder which enables them to float in the water, but sharks have no such bladder. Since cartilage is lighter than bone, it helps to keep a shark from just sinking to the bottom of the ocean. A shark doesn't have as many moveable parts as a bony fish, which in some ways makes a shark a little more clumsy. But cartilage is more flexible than bone, so a shark can turn around in a smaller space than a bony fish. Sharks keep growing cartilage as long as they live, and have extra mineral deposits in their jaws where they need extra strength, (the better to bite you with).

NOSTRILS:

Sharks do have noses, but they only use them for smelling, not for breathing. You'll find their pair of nostrils on the underside of their snouts. Some species, like the Nurse Shark, even have some extra smellers called nasal barbels, which stick out near the nostrils and mouth.

GILLS:

A shark has several pairs of gills on either side of its head, unlike other fish who only have one gill on each side. You probably breathe through your nose and mouth, but a shark only uses its nostrils for smelling.

Sharks have five to seven gill slits on each side of their head, unlike bony fish which have one gill on each side. As water passes over their gills, oxygen is absorbed by the blood in the gills and transported from there to the rest of the body.

Some sharks have small openings called spiracles behind their eyes, at the top of the head. Spiracles are sort of like baby gill slits. The more active, fast swimming sharks seem to have outgrown the need for these spiracles, and only have very tiny ones or don't have them at all.

TEETH:

Shark teeth are in parallel rows. In the front row are the teeth they use to catch and eat their prey. Several rows of replacement teeth keep growing behind the teeth they are using. As their teeth fall out, the new teeth come forward. Sharks keep growing new teeth as long as they live.
Studies by scientists at Mote Marine Labs have shown that, on average, a Nurse Shark will replace each front row tooth every ten days to two weeks during the summer, when actively feeding, and every one to two months during the winter, when they are less active.












THE LATERAL LINE:

The lateral line is a sense that we human do not have. "The lateral line is a fluid filled canal that is lined with tiny hair like receptors that are attuned to vibrations made by prey." (Smith 11). These lateral lines are located just under the skin on the shark's snout and along both sides of the body. These lines are also in bony fish. Fish (sharks included) can also use these lines to sense water currents and pressures and even sounds. Some say that the bumping behavior of sharks allows external taste receptors to see if the organism is edible (this may explain why sharks often bump objects).

BODY TEMPERATURE:

A few of the larger species, such as the shortfin mako, Isurus oxyrinchus, and the great white, are mildly homeothermic - able to maintain their body temperature above the surrounding water temperature. This is possible because of the presence of the suprahepatic rete, a counter current exchange mechanism that reduces the loss of body heat. Muscular contraction also generates a mild amount of body heat. However, this differs significantly from true homeothermy, as found in mammals and birds, in which heat is generated, maintained, and regulated by metabolic activity.

Works Cited

Digest, Reader's. Sharks. New York: n.p., 1998. 
Ellis, Richard. The Book of Sharks . N.p.: n.p., n.d. 
Martin, James. Great White Sharks. Minneapolis: Capstone , 1995. 
Shark Facts. 26 Feb. 2008 .