Sharks

Facts about sharks:

Some facts about sharks are that they can live up to 20-30 years in the wild. Their is many types of sharks like the great white, tiger shark, whale shark, and so many more other sharks that you will be able to reading later on about. A shark's average speed is 8km/h as an adult. Sharks have been roaming Earth for about 450 years. This is because sharks can easily adapt to a new environment.
Sharks don't only live in the ocean. They can be found in many places like in lagoons, creeks, small swamps, and rivers. They are also found in cold and warm weathers.
Sharks eat depending on their environment, food source, and what type of shark they are. Meat eaters eat fish or even other sharks. They may sometimes go for a bigger meal like a dolphin or a sealion. Non-meat eaters eat small aquatic life such as mollusks and clams. These sharks usual live close to the bottom. Sharks also have a powerful jaw that help them eat their pray.
Sharks reproduce easily because they have almost no enemies to harm the young pups. Right when the pups are born they know how to survive on their own. Some sharks use asexual reproduction to have pups too. This is rare and will probably only happen when they are kept in captivity.
Sharks have senses that they need to survive in the wild. They use these senses to find their pray. A shark's sense of smell is the strongest sense a shark has. It can smell a drop of blood from miles away. They have a good eye sight for being in the water, but they still can confuse a person for a colorful fish. Sharks can hear well. They have two openings in the sides of their head which leads to their hearing. Their taste buds aren't on their tonge, but all over the mouth. These are a shark's senses.
Sharks have cartilage in their skeleton rather than bones. This helps them move at fast speeds in water. Sharks don't have bones, so they rely on dermal denticles to help them keep their body shape right. Denticles are the reason a shark's skin is so rough. A shark's jaw is in two separet parts and not attached to the scull. This allows them to have a powerful grip on their pray. They have various rows of teeth and it's shape depends on the shark's diet. Sharks have large teeth and they are very sharp. Sharks are constantly losing teeth. The back rows of teeth will move forward to the spaces, so the shark can have a full set of teeth in the front. It is estimated that in a shark's life time they will go through 30,000 teeth. Sharks have a unique liver. They use their liver more differently than us. They use it to store oil, which is used to eat less. The more oil they store the less they have to eat. Sharks have different sizes of tail depending on their size. Sharks use their tail to move fast in water or to simply glide in the water. All types of sharks have fins. They have two sets of fins to help them move around. Sharks have a dorsal fin, sometimes even two depending on the species. They help with balancing. They have an anal fin in the bottom of them. Which also helps with balancing.
Scientist don't really know how sharks communicate because they are usually loners. Sharks have a very good hearing, so it is believed that they hear other sharks and that is how they communicate. They can also use their senses to pick up electrical currents or vibrations of other sharks and that is also believed to be a way of communication. Sharks also use aggression to communicate. For example, when a shark gets it's pray another shark will try to take it away. This is a way of communication, but can turn into a battle. Sharks mostly use body language to communicate and not sounds. When male sharks are looking for a mate they will bite the female on the back to communicate. We are yet to find out how shark's communicate. It is simply a theory.
According to fossil findings sharks have been on Earth for more than 450 million years. Sharks have evolved in many ways through out the years. Their has also been findings of sharks that are now extinct. Earth today has more than 1,000 species of sharks and their is probably more than that already extinct, so more than half species of sharks will never be seen on Earth again. Sharks used to be small almost like fish and some were like eels. Their teeth were diferent as well. Their teeth used to be smooth instead of sharp. This means that they used to eat plants in the water. This would soon lead them to eat other animals because of the lack of plants. Sharks still have the same skeleton. Sharks are able to adapt to salt and fresh water too. They can also evolve to different temperatures. All of this will help sharks keep on evolving.
You will be able to read about specific types of sharks later on.