Sharks By: Caroline Bell Table of Contents Introduction………………………………………………………………………..3 Species of Shark…………………………………………………………………...4 Shark Behaviour…………………………………………………………………...7 Shark Attacks……………………………………………………………………..10 Shark Habitats………………………………………………………………….....13 Prehistoric Shark………………………………………………………………….15 Sharks Influence on the World……………………………………………………17 Conclusion………………………………………………………………………...19 Works Cited ………………………………………………………………………20 Images Cited………………………………………………………………...…….22 2 Introduction Last summer I was watching Shark Week on Discovery channel, when sharks as an expert topic clicked in my mind. At the time, I was more interested in one of my other topics, and I thought that sharks would be a last minute topic. Then, after doing some preliminary research, I noticed sharks were being treated badly and I was interested in knowing more and helping to save them. At first I asked myself; why are people afraid of sharks? Then I realized the bigger question; why are people hurting sharks? Since then I have discovered that people injure these predators because they are afraid of them. I have also learned that sharks benefit our world and without them our Earth would fall apart. 3 Species of Shark Some sharks are so weird looking, it is hard to peer at them. Megamouths are rare and incredibly bizarre-looking. These sharks get their name from their four foot wide, strange looking mouth. They are the smallest filter-feeders of all at only sixteen feet long. Since 1976 there have only been thirty-five megamouth sightings. It is hard to find out more about these gentle giants, but scientists do know they are unbelievably weird. Goblin sharks definitely earn their name. Even though goblin sharks are only about ten feet in length, their snout is about three feet long. These sharks protrude their jaws from their heads to catch and trap prey. Their teeth are long and sharp, a little like the Sand Tiger shark’s teeth. Sadly, they have rarely been seen alive. Goblin sharks are the freaks of the weird shark world. Cookie Cutter sharks have a bizarre way of hunting. These sharks use their lips as suction cups to attach to other animals. Once attached, the Cookie Cutter shark will bite and move around in a circle. The bite of this shark is almost a perfect circle. They bite into whales, dolphins, seals and occasionally submarines. Cookie Cutter sharks are a little eerie to look at, but they are small and their bite is not deep enough to hurt an animal extremely. There are some sharks that individuals know little about, but there are also some sharks that people know well. Great White sharks are one of the most well - known sharks, probably because they are usually the shark that is seen attacking 4 people. The “great” in Great White is given to these sharks to describe their sheer size and power. Another name for this shark is the White Spinner or White shark. They can leap straight out of the water from below to surprise their prey. These sharks mostly eat seals, tuna, dolphins, seabirds and occasionally other sharks. Great Whites are big with many teeth, but attacks on humans are still rare. The Great Hammerhead is one of the most identifiable sharks. These sharks will use their big heads to pin down their prey to the seafloor. They eat small fish, stingrays and squid. This shark's big head and its slightly tall, slightly curved dorsal fin are keys to identifying the shark. “No one shark is the same,” said EyeWitness Books, and that is illustrated well in the Great Hammerhead. Lemon sharks are one of the most common but not well-known types of sharks. They live in warm coral reefs. These sharks hunt and swim at night and rest during the day. Their yellowing color gives a Lemon shark its name. They eat fish, small sharks, squid, seabirds and crustaceans. Lemon sharks are calm, social creatures and it is not likely for a Lemon shark to attack people. There are many different kinds of sharks now endangered all over the world. Blue sharks are one of the many species of shark that are at a low risk of becoming endangered. These sharks get their name from their indigo coloring. Like many sharks, the Blue sharks numbers are decreasing because of overfishing. Meat and fins of the Blue shark are also eaten. Their skin is used for leather products. Blue sharks are beautiful creatures so it is sad to see them at risk of going endangered. 5 Sand Tiger sharks are at a high risk of extinction in the wild. These sharks reproduce slower than they are being killed. Sand Tigers, also known as the Ragged Tooth and Gray Nurse shark, live over sixteen years in the wild. They are also considered vulnerable like the Blue shark. People catch these sharks for their ragged teeth, which give them their other name, for jewelry and a keepsake. Sand Tigers are now protected in many states but are endangered in the wild. Angel shark numbers are declining because of bycatch and overfishing. These sharks have been caught in bycatch and usually end up dead. They cannot be found in their old habitats, because they have been chased out by fishing. Many different kinds of Angel sharks are in immediate danger of going extinct. Fisheries used to catch these sharks for food. Angel sharks are protected in many places, but are still critically endangered. Many sharks are going endangered and knowing more about them can save them. 6 Sharks Behavior Not all sharks sleep, but when they do they sleep with their eyes open and are aware of their surroundings. Some sharks experience short resting periods, others do not. Shark behavior is still being studied by scientists. Sharks can be predictable, but they are wild animals, and scientists do not always know what they are thinking. It has been said sharks are unintelligent, but studies show they are actually very intelligent for their small sized brain. Sharks are unpredictable, but usually it is easy to observe their behavior and how it changes to find out what they are thinking. Circling is an example of hunting behavior. The shark will circle its prey from below for the element of surprise. While slowly closing the circles, the shark will become more hostile. After circling, the shark will start to criss-cross toward its prey. When the time is just right, and the prey is least expecting it, the shark makes a violent attack. By studying these behaviors, humans can be safer by avoiding contact and interaction with circling sharks. There are more hunting ways than just circling. Some types are filter-feeding, tearing, or swallowing their prey whole. Filter-feeding is most common in bigger sharks that eat smaller animals like krill. These sharks have small gill-rankers inside their mouth. Water flows into the mouth and through a 7 filter-like structure called gill-rankers to catch the krill and microscopic sea creatures in the water. Tearing is the most common way of hunting for sharks like the great white and tiger shark. To begin, the shark will take a test bite to see if it likes the food. If the shark enjoys its catch, then it will tear meat bit by bit off the prey’s skeleton. The first couple of bites usually injure the prey so they cannot escape out of the shark's jaws. This is also one of the most violent ways sharks hunt their prey. Swallowing their prey is not the most common way of hunting, but there are multiple types of sharks that have adapted to swallowing their prey whole such as the Mako. Instead of going up to the prey and taking a test bite, the shark will swim at the victim and eat it in one bite. These three feeding strategies are used depending on the shark. A feeding frenzy is when many sharks get over-excited and eat anything, including each other. Feeding frenzies are dangerous to be around and can occur when many tiny bits of food are floating around in the water, and, one by one, sharks notice and start to go deranged. They can be dangerous for any animal in the area. Even bigger sharks will avoid getting involved in a frenzy involving smaller sharks. 8 It has been said that sharks have a sixth sense for hunting. This is the electrical sense. All animals give off an electrical field. Sharks have tiny pores on their snout called Ampullae of Lorenzini which allows the shark to pick up these electrical waves through the water. This lets the shark know which animals are injured or sick and which ones are strong and healthy. Naturally, the shark will go for the easy prey, the sick or injured prey. This sixth sense is incredibly effective. Not accidentally, some sharks travel in groups. These groups can include more than 100 sharks. Sharks can show cooperative behaviour within their packs. They work together to do things, like move a whale. The dominant sharks of their group will often nip smaller ones to get to the middle of the group. Not all sharks travel or hunt in packs. Sharks like the hammerhead prefer to travel in groups, while sharks like the great white favor hunting and traveling by themselves. There are many acts that show social behaviour between sharks. Smaller sharks sometimes dominate the bigger ones, usually over food. Nurse sharks, also known as the “lazy shark,” are known to be the most social shark. Many sharks are incredibly social between themselves. 9 Shark Attacks Not only does Florida have the highest number of shark attacks in the US, but it holds 25 percent of the world's attacks.