- published: 23 Sep 2013
- views: 10900193
Sharks are a group of 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.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. Sharks have a covering of dermal denticles that protects their skin from damage and parasites in addition to improving their fluid dynamics. They have several sets of replaceable teeth.
Jonathan travels to Mexico for an up close encounter with Bull sharks, infamous for the fact that they are known to be the most dangerous species of shark to humans. He gets to try a chain mail anti-shark suit, and meets a biologist who is studying the sharks to learn more about their population and habits. ********************************************************************** If you like Jonathan Bird's Blue World, join us on Facebook! https://www.facebook.com/BlueWorldTV Or Twitter! https://twitter.com/BlueWorld_TV On the Web: http://www.blueworldTV.com **********************************************************************
**This may not be appropriate for our younger viewers.** Follow up video showing the full story here: https://youtu.be/UffOvJnD-4s This is not our usual kids content and Gabe and Garrett did not go on this trip, this video is from my trip to Guadalupe Island (I'm their dad). On a recent great white shark cage diving trip we experienced a very rare event, a shark breaching the side of the cage. What might appear to be an aggressive great white shark trying to attack the cage, this is not the case. These awesome sharks are biting at large chunks of tuna tied to a rope. When a great white shark lunges and bites something, it is temporarily blinded. They also cannot swim backwards. So this shark lunged at the bait, accidentally hit the side of the cage, was most likely confused and no...
Have you ever imagined being attacked by the shark? In this video we take a look of the top 5 horrific great white shark attack footage caught on tape 2016. How scary it is to come face to face with the shark? Commend down below and share your thought about these shark attack videos. ⚑ Join our community ⚑ ■ Facebook : https://www.facebook.com/StuntsLife ■ Twitter : https://twitter.com/StuntsLife ⚑ Tags ⚑ great white shark attack shark attack shark attack 2016 bull shark attack white shark attack shark news shark sightings shark attack video footage shark videos shark attack video great white shark videos latest shark attacks sharks eating people shark bites best shark attack 2016
top 10 bizarre and crazy objects eaten by sharks Subscribe to our channel: http://goo.gl/9CwQhg For copyright matters please contact us at: david.f@valnetinc.com Other Videos You Might Like The Biggest LIES Famous People Tried To Hide https://www.youtube.com/edit?video_referrer=watch&video;_id=kWrmPFq2d7A 10 Most Bizarre Shark Species Ever Discovered https://www.youtube.com/watch?v=jABJ-jKHChE Description: The Strangest Things Swallowed by a Shark People love sharks and we just can’t seem to get enough of them. Where did it all start? Well, to be honest ever since humans have taken to the sea they have been in awe of the powerful underwater predators. In 1975, interest was again piqued thanks to the classic thriller Jaws. Today, week long television specials and ridiculous films about to...
Subscribe to Naked Science - http://goo.gl/wpc2Q1 Every other Wednesday we present a new video, so join us to see the truth laid bare... For 400 million years, sharks have dominated the Earth's oceans. They have survived 5 planetary mass extinctions to become the top predators of the sea, honed to an evolutionary perfection. But what shark species is the most deadly? And where in the world is it least safe to venture in to the water? Naked Science travelled across the world from Australia to California to find out.
#SharkWeek http://www.discoverygo.com Shark experts Jeff Kurr and Andy Casagrande are in a small boat surrounded by giant great whites in this heart-pounding scene from Lair of the Mega Shark. Subscribe to Discovery: http://bit.ly/SubscribeDiscovery Join us on Facebook: https://www.facebook.com/sharkweek https://www.facebook.com/Discovery Follow on Twitter: https://twitter.com/SharkWeek https://twitter.com/Discovery
Is a 60-foot prehistoric shark named Megalodon still out there? Sightings of massive sharks around the world suggest to some that it's possible. Megalodon Shark Sightings Reported Megalodon shark sightings have some people wondering if the most formidable predator the ocean has ever seen might still be alive today, even though science and common sense tell us it's impossible. At maximum lengths of up to 60 feet, Megalodon was the largest shark that ever lived and the apex predator of its day. This terrifying monster lived at a time when the ocean was a very different place, and it went extinct long ago. Why, then, are there reports of massive sharks thirty feet long or more from around the world? Is it possible mainstream science has it wrong, and the Megalodon shark is still out there...
Today we look at 5 Horrifying Shark Encounters Caught On GoPro 2016 If you enjoy Top 5 Horrifying Shark Encounters Caught On GoPro Please Like, Comment and Subscribe for more Horrifying Videos. We will be uploading Top 5 Shark attacks Caught On GoPro. Subscribe for more Top10s - https://www.youtube.com/channel/UCQiwdqoPFHE6IWORhZQ3RrQ?sub_confirmation=1 (Twitter) https://twitter.com/WeWantMoreFacts (Snap Chat) WeWantMoreFacts What Do You Want To See Next Comments Below. We aim to bring you facts and crazy thing we think you would not know, Movies,Cartoons,Games,Real life stuff and much much more. Outro Music - https://www.youtube.com/watch?v=rd1U-7n0Z3Y (Check out some previous videos) TOP 10 UNEXPLAINED MYSTERYS - https://www.youtube.com/watch?v=Fvj5bgEqRV0 TOP 10 POKEMON GAMES ...
MÁLAGA, SPAIN — Scientists from Spain have discovered an Atlantic sawtail catshark embryo with two heads, a threatened shark species found only in the western Mediterranean. Their findings were recently published in the Journal of Fish Biology, leading the scientific community to wonder what may be causing these abnormalities. In 2013, fishermen working off the Florida Keys caught a pregnant bull shark, and when they cut her open, they were stunned to find two unborn offspring, one of whom was a mutant. The fetus was the first two-headed bull shark on record. Most cases of the two-headed sharks are conceived by blue sharks, as they can have up to 50 babies at one time. Scientists aren’t exactly sure what’s causing the bizarre birth defect, but theorize overfishing in some regions...
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I went to the marina saw a man in a speedo scratching himself and staring at sharks his shirt was unbuttoned long grey chest hairs and the sharks just kept swimming more bored than annoyed and the man on the tape says that they'd suffocate if the sharks would stop swimming in circles even though there's no place for them to go in this aquarium they just keep swimming in circles they're such noble creatures the marina's main feature and they glide through captivity with oceans more dignity than we'll ever know judging by that speedo and the man on the tape says that they'd suffocate if the sharks would stop swimming in circles even though there's no place for them to go in this aquarium they just keep swimming in circles