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Tags: megalodon sharkmegalodon history in hindimegalodon ke baare mein batayesharkshark in hindishar information in hindishark teethshark ki history`rarefactwhale shark ke baare mein batayeshark facts in hindiwhale facts in hindishark factsshark ki jasnkarimegalodon factsshark history in hindirare factshark informationshark historyshark ke baare mein batayeshark facts videosshark videos in hindishark ke daant

Description: HELLO GUYS HOW R U ALL , IN THIS VIDEO IM TALK ABOUT SHARK. #SHARK #SHARKFACTS #WHALESHARK Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (or Selachii) and are the sister group to the rays. However, the term "shark" has also been used for extinct members of the subclass Elasmobranchii outside the Selachimorpha, such as Cladoselache and Xenacanthus, as well as other Chondrichthyes such as the holocephalid eugenedontidans. Under this broader definition, the earliest known sharks date back to more than 420 million years ago.[2] Acanthodians are often referred to as "spiny sharks"; though they are not part of Chondrichthyes proper, they are a paraphyletic assemblage leading to cartilaginous fish as a whole. Since then, sharks have diversified into over 500 species. They range in size from the small dwarf lanternshark (Etmopterus perryi), a deep sea species of only 17 centimetres (6.7 in) in length, to the whale shark (Rhincodon typus), the largest fish in the world, which reaches approximately 12 metres (40 ft) in length. Sharks are found in all seas and are common to depths of 2,000 metres (6,600 ft). They generally do not live in freshwater although there are a few known exceptions, such as the bull shark and the river shark, which can survive and be found in both seawater and freshwater.[3] Sharks have a covering of dermal denticles that protects their skin from damage and parasites in addition to improving their fluid dynamics. They have numerous sets of replaceable teeth.[4] Well-known species such as the great white shark, tiger shark, blue shark, mako shark, thresher shark, and hammerhead shark are apex predators—organisms at the top of their underwater food chain. Many shark populations are threatened by human activities. Until the 16th century,[5] sharks were known to mariners as "sea dogs".[6] This is still evidential in several species termed "dogfish," or the porbeagle. The etymology of the word "shark" is uncertain, the most likely etymology states that the original sense of the word was that of "predator, one who preys on others" from the Dutch schurk, meaning "villain, scoundrel" (cf. card shark, loan shark, etc.), which was later applied to the fish due to its predatory behaviour.[7] A now disproven theory is that it derives from the Yucatec Maya word xok (pronounced 'shok'), meaning "fish".[8] Evidence for this etymology came from the Oxford English Dictionary, which notes shark first came into use after Sir John Hawkins' sailors exhibited one in London in 1569 and posted "sharke" to refer to the large sharks of the Caribbean Sea. However, the Middle English Dictionary records an isolated occurrence of the word shark (referring to a sea fish) in a letter written by Thomas Beckington in 1442, which rules out a New World etymology.[9] Shark teeth are embedded in the gums rather than directly affixed to the jaw, and are constantly replaced throughout life. Multiple rows of replacement teeth grow in a groove on the inside of the jaw and steadily move forward in comparison to a conveyor belt; some sharks lose 30,000 or more teeth in their lifetime. The rate of tooth replacement varies from once every 8 to 10 days to several months. In most species, teeth are replaced one at a time as opposed to the simultaneous replacement of an entire row, which is observed in the cookiecutter shark.[24] Tooth shape depends on the shark's diet: those that feed on mollusks and crustaceans have dense and flattened teeth used for crushing, those that feed on fish have needle-like teeth for gripping, and those that feed on larger prey such as mammals have pointed lower teeth for gripping and triangular upper teeth with serrated edges for cutting. The teeth of plankton-feeders such as the basking shark are small and non-functional.[25] DONT FORGET HIT : L-I-K-E S-H-A-R-E S-U-B-S-C-R-I-B-E AFFILIATE LINKS : MY SET UP : MY PHONE : amzn.to/2n85SZR MY COMPUTER : amzn.to/2Gcqg4I FOR YOUTUBERS : BEST MIC FOR YOUTUBERS : amzn.to/2E3psyb BEST CAMERA FOR YOUTUBERS : amzn.to/2n7AF8K BEST LAPTOP FOR YOUTUBERS : amzn.to/2n3F78E SOCIAL LINKS : FACEBOOK : facebook.com/GuriKhindaOfficial INSTAGRAM : instagram.com/guri_khindaofficial CONTACT FOR SPONSORSHIP : GURIQBAL301@GMAIL.COM BACKGROUND MUSIC :