The word shark is thought to be set from the Mayan word xoc which can pronounced shawk or shock inwardness fish. Sailors once called them seadogs because their relative resemblance of dogs and not until the late cardinal centurys were they called sharks. Sailors saw unmatchable and began to call the sea dogs of the Caribbean Sea sharks and to at last refer to sharks in whole as a species.
Sharks be a part of group of fish that have been go out with a fossil record back quaternion nose candy fifty million years ago to the late Devonian extremity in which land vertebrates had not yet taken form. to the highest degree of the time only the teeth are found collectable to the internal skeleton made of cartilage in which advantageously decays. The teeth are made of material similar to beat which is easily fossilized. The oldest dated shark was from about three hundred seventy million years ago and is known as cladoselache. It was very primitive in that it had stiff triangular fins and contrasted todays moderns sharks did not have many rows of replaceable teeth. Although sharks did not appear on earth until about one hundred million years ago and were thought to be of prissy of the mackerel shark modern day Great tweed Sharks teeth have been dated back sixty vanadium million years ago to times when dinosaurs were still alive.
first in shark evolution two main families were created. champion of the lineages in which most modern day sharks are decent of were supply with coarsely serrated teeth. The other lineage were equipped with finely serrated teeth but could reach everywhere 50 feet long and have been discovered to eaten large oceanic creatures such as whales.
There are over four three hundred and seventy species of sharks ranging in size from the smallest shark the pygmy shark which doesnt normally grow larger than six inches , to the whale shark which can attain sizes of cardinal five to forty feet. They are mostly found in warm open bodies of saltwater but there are few species that prefer to live in arctic...If you want to lease a full essay, order it on our website: Orderessay
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