Data Bases • Custom Term Papers • Free Term Papers • Free Research Papers • Free Essays • Free Book Reports • Plagiarism? Links • Top 100 Term Paper Sites • Top 25 Essay Sites • Top 50 Essay Sites • Search 97,000 Papers @ DirectEssays.com • Search 101,000 Papers @ ExampleEssays.com • Search 90,000 Papers @ MegaEssays.com Free Essays • Term Paper Sites • Chuck III's Free Essays • Free College Essays • TermPaperSites.com • My Term Papers • Get Free Essays • Essay World • Planet Papers	Search Lots of Essays Back to Subjects - Animal Science & Zoology The Great White Shark The Great White Shark Beginning with the simplest one-celled organism, an extraordinary animal rose in the murky waters entitled to a non-comparable killing-eating machine. This organism has become nature’s most genuine and most successful creature that it has remained unchanged for over 250 million years. Nature finally invented the perfect king of the sea. This animal has given the sea it’s “living” adjective; in turn, it was entitled— the “great white shark.” The Great White Shark derived from a series of evolutionary advancements that took several billion years. It began with the derivation of the vertebrates—the Phylum Chordata. Here, the Class Agnotha came to existence. Some features of Agnotha are the presence of a cartilage skeleton, nine gill slits (turning into five gill slits in sharks, where the first four became the jaw), and fins. Sharks belong to the class Chondrichthyes—a more elaborated organism. Jaws derived from the first four gill slits, spiral valve, and productive fins. The fins are amongst the most important advancements made by the Fixed rigid rods support the fins. The sharks have five different types of fins. They have paired fins that lift the shark, as it is able to swim; paired pelvic fins, which stabilize the shark and letting it steer to reach its prey in a more effective manner; dorsal fins also further aide the shark in stabilization as well as the anal fin. For propelling, the shark uses the caudal fins. The caudal fins allow the shark to charge directly toward its The great white shark’s size is inevitably recognizable, but it was actually even bigger, much bigger. It was called Carcharodon megalodon years ago. This creature is still believed by some to live down in the waters, where it would be almost impossible to reach shore because of its monstrous size. It is over forty feet long and believed to be able to eat a school bus whole! Of course, the great white average length is anywhere from twelve to sixteen feet long, but they are not restricted to those limitations. The shark’s outer “skin” is covered by something called placoid scales. These scales are like tiny teeth and have the same structure as the shark’s teeth. They are also called dermal denticles. The placoid scales are arranged in a regular patter. Although they do not grow in length, they grow to cover the shark’s surface area as the shark grows. Sometimes, the placoid scales create tiny whirlpools behind each scale, enabling the shark to swim more efficiently. The great white shark has two types of muscles-red and white. Red muscle is aerobic; thus, it needs oxygen to function. This muscle contains myoglobin. The main function of the red muscles is used just for swimming. The white muscle is anaerobic- doesn’t need oxygen. White muscles primarily function for sudden bursts of speed when One cannot forget to realize the teeth of the great white, as well as its powerful jaw structure. The teeth are actually modified, enlarged placoid scales. The teeth aren’t anchored in the jaw; they are just embedded on the gums. Unfortunately, when the great white shark eats on its prey, it sometimes loses or breaks the tooth by the flesh. Luckily, sharks have developed a special feature that enables it to replace its missing tooth. They have developed rows of teeth, each tooth moving up to replace the missing one. A whole broken row of teeth can be replenished, just like a conveyor belt. Each tooth, though, has a different shape, changing according to its necessity. The great white has triangular, serrated-edged teeth anywhere from one to two inches long. With this feature, the shark is able to tear through the flesh for its meal. The jaw of the shark is made up of strong bone tissue. It must be very powerful because the shark is designed for feeding. In link to the teeth is the shark’s olfactory sense, the best in the seas. It is impossible to imagine how sensitive the olfactory nerves are. The great white shark can sniff out one drop of blood miles away. Even if one drop of blood is diluted with billions of gallons of water, a shark can still detect it. This is possible because of fluid filled sacs on both sides of the fish called lamellae, running the entire length. The walls of the tubing are so sensitive that vibrations as far away as eight miles can be felt. The shark contains a lateral line system below the skin of the head and along the sides of the body. The lateral lines contain sensory cells called neuromasts. Any turbulence, current or vibrations stimulate these hairlike structures. It mainly senses low-frequency vibrations. The walls of the tubing are so sensitive that vibrations as far away as eight miles can be felt. The shark has twenty to thirty little black “freckles.” Not only do the freckles pick up the scent of blood, but also electrical fields as tiny as .005 microvolt. Each organism in the creature gives out a small electrical field, and since the water is such a great conductor, this is very advantageous to the shark. Sharks attack bleeding victims, not only because the scent of the blood, but because the blood releases so many ions in the water, intensifying the electrical field. The electrical fields are detected by the Ampullae of Lorenzini. External pores cover the surface of the shark’s head. Each pore connects to a jelly-filled canal leading to the ampullae. The ampullae detect the weak electrical fields at short ranges. The Amupllae of Lorenzini can also detect salinity, magnetic fields, temperature change as well as changes in water pressure, and mechanical stimuli. The shark’s brain is simple; it consists of a forebrain, midbrain, and a hindbrain. The forebrain is mainly made up of the olfactory lobes. These detect smell and scent. The forebrain, also known as cerebrum in other vertebrates, is not used in “learning” with the great whites. The midbrain contains the optic lobes, dealing with sight. Much of the sensory information is coordinated, and where directions are sent out for movement. The hindbrain is the biggest region. It must be big because it is needed to control and coordinate life functions and motions. These include: balance, swimming, heartbeat, blood pressure, digestion, as well as secretion. The great white’s digestive tract begins with the short and wide esophagus. The esophagus leads to the stomach, leading to a spiral valve. The spiral valve is twisted to increase the surface area, which increases nutrient absorption. After the spiral valve, the digestive tract leads to the rectum and to the cloaca. The cloaca is the opening for the urinary, digestive, and reproductive systems. The shark’s heart has only two S-shaped chambers. The blood flows from the heart to the gills and then to the body tissue (red muscles). The temperature of a great white can be a bit higher than its surrounding environment, usually fourteen degrees Fahrenheit higher. This heat is because the red muscle. The blood returning to the heart from the muscle is warmer than blood traveling from the heart to the muscle because muscle-generated heat warms the blood circulating through the red muscle. Because the arteries and veins are so close to each other, heat passes from warmer veins to cooler arteries within the shark’s body. Sharks have low blood pressure. The walls of the pericardium are rigid, creating suction within the pericardium to maintain the flow of blood. To circulate blood throughout their bodies, the great white shark must swim A shark’s liver is made of two large lobes that concentrate and store oils and fatty acids. The liver functions as an energy storage and buoyancy. The shark’s liver makes up anywhere from 5% to 25% of its total body weight. This is one of the main reasons The great white shark has a very basic eye structure, but laterally compressed. The lens is relatively large and spherical. They are well suited for seeing in dim light and are particularly sensitive to moving objects. They can see in dim light because of the abundance of rods; therefore, the great white can identify between light and shadow. The eye has a layer of reflecting plates called the tapetum lucidum behind the retina. They act as mirrors to reflect light back through the retina again; moreover, they have better sight than cats. A shark’s pupil is able to dilate and even contract. Few cones are present, so we know that shark can barely distinguish colors. Discussing matters with color, the shark’s color has a great advantage. In most sharks, especially the great white, the ventral side is white in color and the top and sides vary in shades of brown and blue. The great white is on the dorsal and lateral sides. The countershading is an essential type of countershading; the dorsal side is darker, and the ventral is lighter. The light ventral side blend in with the lighter surface of the sea if you view the great white shark from below. If viewing the great white from the surface looking down, the blue blends with the depths of the ocean. Thus, predators or prey cannot tell the difference if the shark is approaching them. The great white sharks have used the water properties to their own advantage. To overcome the drag and resistance, the shark uses thrusts. The shark does this by “swishing” its body and tail. This is possible by the third law of motion: “when a force on a body causes an action, it is opposed by an equal and opposite reaction.” While the shark is swimming, its body moves side to side, pressing the surrounding water. The sideways motions cancel each other out and the shark is able to swim more effectively. The caudal tail gives the final thrusts to pick up more speed. The great white can reach a speed of thirty-five miles per hour! When the great white is ready to catch its prey, it first observes the prey very carefully. Then it does a quick all-powerful thrust with its jaw wide open to bite the prey. Its powerful jaw envelopes the prey, usually the prey will bleed to death. They feed on fish, rays, smaller sharks, small harbor seals, and sometimes even sea lions, elephant seals, and small toothed whales. The great white shark, though, only hunts when it is hungry. Because 70% of its brain is used for prey tracking, it is no wonder why they are excellent predators. A great white though can go a month without eating if it had a very Many people believe that great white sharks just want to eat humans; this is on the contrary. In the shark’s point of view, when humans are swimming, they look like a vulnerable fish. This is why they attack humans. Also, if you are a surfer, from below looking up, the shark only pictures a fish’s body structure. Out of the 1026 shark attacks, only 294 have been great white sharks attacks in the last ten years. Only 18% of these Great white sharks are abundant off the waters of California. The Farallon Islands has become the place where sharks go to feed. This is because the northern elephant seal, the California sea lion, the Steller sea lion, and the harbor seals live on this area. Great white of course aren’t restricted to the waters of California, they are found all over the world as long as there is an abundance of its prey. It is not hard to think of the Great White Shark as one of the most feared animals in the water. The release of Jaws in the 1980s gave Americans a bigger fear of this creature. Since then, sharks overall have become overfished. Each year over 700,000 metric tons of sharks are harvested each year, the great white being one of the most killed. Sharks play a vital role in the ecosystem. They keep the ecosystem populations low by killing other animals to balance off nature’s reproduction. If it were not for sharks, marine population would increase considerably. Others would eliminate available food because only the stronger ones would survive—survival of the fittest. Sharks may not continue to follow its planned role in nature, if humans continue killing them. It seems that Ernest Hemmingway was right in his book The Old Man and the Sea; if we could reach the stars we would kill them too. It is a blessing miracle that they are so far away we cannot reach it. But maybe one day….we will reach them, and kill them in all their glory like all other animals on Earth. Bibliography: Word Count: 2121
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