Introduction To Shark

                                  Sharks are a large group of fish that have inhabited the oceans for over 400 million years, even before dinosaurs populated our planet. They belong to the superorder Selachimorpha, and new sharks have specific characteristics like a cartilaginous skeleton, five or six pairs of gills and several rows of teeth.Ancient Sharks lived before land vertebrates populated the earth and even before many plant species developed. While they were very different from those found today, sharks have been on this planet for a long time. 

Evolution

                   Fossil evidence shows that sharks populated the planet before the dinosaurs existed, that is, more than 400 million years ago. Since the skeleton of the shark is composed of cartilage, the only thing preserved from prehistoric sharks are fossil samples of the dermal denticles and teeth, but there are some exceptional cases of preserved skeletons.The first fish appeared on Earth about 510 million years ago. They were small, jaw-less beings called ostracoderms. Evolution did its job, and that’s when the first prehistoric sharks first appeared. 

Diet

          Most species of shark eat things like fish, crustaceans, mollusks, plankton, krill, marine mammals and other sharks. Sharks also have a very acute sense of smell that allows them to detect blood in the water from miles away. 

Facts

    1) Shark can detect movement in water.    2)Shark lives 100 t0 150 years.    3) Sharks mature slowly and reach reproductive age anywhere from 12 to 15 years.      4)  Sharks generally have about 45 to 50 teeth  but that’s just the front row teeth.     5) Sharks have complex and varied ways of giving birth to their young. Some lay egg  and some give birth.   6) Sharks live in all seven of the world’s oceans, but they’re not live in salty water except some of them.   7) Sharks predate the dinosaurs by 200 million years.   8) Your odds of getting attacked and killed by a shark are 1 in 3,748,067.    9)Shark dose not sleep like human. Shark take rest by releasing its body and float in water.  10) Sharks Are Not Vicious Man-Eaters.