Rachel

Sharks of the World

Sharks have fascinated me for three or four years. I wanted to know about different types of sharks. One of my sub topics is breeds, so I gathered information about many types of sharks. I picked Sharks of the World for my topic because I find it interesting and wanted to learn more. I hoped to learn more about the shark's anatomy, their eating habits, and habitats. I wanted to learn about the different breeds' characteristics. I learned everything I expected to learn. It was easy for me to find information on my topic. Information was gathered from shark books, and looking on the Internet. The only thing that was difficult was finding different web sites where I could find a lot of shark information. Depending on the book used, not all of the information was consistent. Sharks use their snout to hunt down food. If there is someone or something bleeding in the water, sharks will be attracted to the scent. They can smell it even from one half-mile distance. This can cause a feeding frenzy. A feeding frenzy is when sharks come from all directions and start to eat. Sharks do not chew their food, they swallow it whole. Sharks often eat things that are floating in the water, such as, an old boot, clothing, or even cardboard. Almost all sharks are carnivores. They eat fish, seals, and even other sharks. Some sharks however are herbivores, eating plankton and other types of seaweed. It takes awhile for sharks to grow. A shark is usually not full grown until it is ten to fifteen years old. Sharks live to be anywhere from twenty five to one hundred years old. A sharks age can be determined by counting the growth rings on it's vertebrates, or backbone. Sharks have from one to one hundred babies at a time. While some sharks lay eggs, others give birth to live babies, called pups. Many sharks do not care for their pups after they're born. The mothers do search for safe places, called nurseries, where they can lay eggs or give birth. There are both salt water and fresh water sharks. Although both can be found in freshwater at times. Sharks have been found in the Mississippi River. It is amazing to know that sharks have also been found swimming up the Amazon River, in Africa. Sharks live in all oceans, from cold to temperate waters, usually cooler than ninety degrees Fahrenheit. Many sharks migrate as water temperature changes with the seasons. Some sharks travel north in the summer to find cooler waters and travel south for warmer waters in the winter. Most sharks are cold-blooded animals. This means that their body changes temperature as the water temperature changes. The largest shark is called the Whale Shark and the smallest is called the Pygmy Shark. The Pygmy Shark can fit in the palm of a human hand. They can grow up to six inches long. A Whale Shark is the exact opposite, growing up to fifty feet in length. Some sharks, such as the Wobbegong are bottom dwellers. If a shark's body is flat, it is probably a bottom dweller. These sharks move slowly across the ocean floor. A shark's body is rather unusual. Their skeleton is actually boneless. Their skeletons are made of a tough elastic substance called cartilage. They have five to seven pairs of gill slits on each side of their body. Most species of sharks have a rounded body shaped somewhat like a torpedo. This helps them to cruise slowly through the water for long distances. It also enables them to move very quickly if necessary. A shark's skin is so tough it can be made into leather. It is covered with tiny tooth like plates called denticles. Sharks have a lifetime supply of teeth. An adult goes through seven to twelve sets of teeth in a year. If a tooth breaks off they have endless rows of teeth to move forward and take it's place. Different species of sharks have different types of teeth, depending on whether they are herbivores or carnivores. Carnivores have very sharp teeth. If you were bitten by a shark you would most likely have to get stitches. Sharks do not hear as humans and animals do. Sharks have no ears, but have the ability to hear in another way. Sharks can "hear" sounds and movements in the water. Vibrations get to the nerves in a shark's head and alerts them. Sharks have five different kinds of fins. They have the pelvic fin, anal fin, the caudel fin, the pectoral fin, and the dorsal fin. The pair of pelvic fins are located under the body toward the tail. They help the shark with its balance. The anal fin is where the shark has its eggs or pups. They have two pectoral fins, one on each side of the lower front part of their body. They lift the shark as it swims. The dorsal fin is located on the top of the shark's back and also helps it to balance like the pelvic fins, as it swims through the water. Most important the shark has a caudel fin that is really part of the tail. The caudel fin has two lobes on it. The shark's speed depends on the size of these lobes. If these lobes are about the same size, then the shark is a very fast swimmer. There are over three hundred fifty species of sharks. Almost all are named after their characteristics. This includes their size, looks, and behavior. One example is the Angel shark, which looks like an angel because of its wing like appearance. A Hammerhead shark looks like a hammer and a Cookiecutter shark gets its name from the way it bites flesh from its prey. There are nine different kinds of Hammerhead sharks. Their eyes are at the end of stalks, which stick out on both sides of their head. They travel in schools, although the reason for this is unclear. Stingrays are their favorite food to eat. The poisonous stinger that the stingray uses does not seem to bother the Hammerhead shark at all. Bull sharks are one of the most dangerous sharks. They can grow up to ten feet long and weigh approximately five hundred pounds. The Bull shark likes to swim in shallow waters near land and sometimes leave the salty water of the ocean to live in fresh water. In the United States, Bull sharks have been spotted in the Mississippi River. Cookiecutter sharks are quite scary looking. Cookiecutter sharks are only about two feet long. They often take a bit of flesh out a prey much bigger than themselves. The Cookiecutter shark cuts small, neat, round holes out of its prey, the way a cookiecutter cuts cookie dough. Great White sharks are huge sharks. The Great White grows to over twenty feet long and weigh more than 5,000 pounds. Their teeth can be up to three inches long and they can live for as long as twenty years. Great Whites are warm-blooded sharks. No one knows much about the Great White or how many exist. Sharks have few natural known enemies. People and other sharks pose the greatest threats. Sharks will usually avoid eating the spiny puffer fish as well. They can blow themselves up inside the shark's throat and choke it. Sharks do not like to eat people but attacks happen due to mistaken identity. Seen from below, a person on a surfboard or boogie board could easily be mistaken as a seal. People have found many uses for almost every part of a shark's body. Shark fins are used in many Asian meals and are quite expensive. Shark oil is used in some skin creams. Their hide is sometimes used as leather, their teeth made into jewelry, and their jaws are sold in shops as souvenirs. I have admired sharks ever since my family started going to the ocean for our family vacations. Doing this project made me learn more than I expected to learn about sharks. There have been many shark attacks due to mistaken identities, which captured my interest. I have decided that I would like to be a Marine Biologist when I grow up. Therefore studying sharks has helped me start my goal. This project was not too difficult because I already had the interest and did reading on my own, prior to the project. The most interesting thing I learned is that there are so many different species. I was quite surprised to learn that some sharks actually make their way into freshwaters. If I had more time I would like to learn how to dive and go diving in the Atlantic Ocean. Then I would learn even more about Sharks of the World.   Glossary anatomy - the structure of animals or plants. carnivores - any animal that consumes other animals. cartilage - a tough elastic, whitish animal tissue. characteristics - a distinguishing trait, feature, or quality. herbivores - an herbivorous animal, like a whale shark. An animal that eats only plants. migrate - to move from one region to another with the change of seasons. nurseries - a place where parents temporarily leave offspring, so that they are safe from predators. plankton - the, usually microscopic, animal and plant life found floating or drifting in the ocean or in bodies of fresh water, used as food for nearly all aquatic animals. souvenirs - something kept, serving as a reminder of a place, person, or occasion. vertebrate - having a backbone or spinal column.   Bibliography A First Look at Sharks; By Millicent (Ellis) Selsam 1979, New York, New York 36 pages Ocean Animals; By Laura Evert 2001, Minnetonka, Minnesota 42 pages Sharks; By Russel Freedman, 1985, New York, New York 40 pages Shark; By Miranda MacQuitty 1992, Westminster, Maryland. 102 pages Sharks, Rays, and Eels; By Christopher Lampton 1995, Racine, Wisconsin. 23 pages

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