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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 Batoidea ( rays and kin).
- Anatomy
- Behavior
- Attacks
- Threats
Like rays and skates, sharks fall into a subclass of fish called elasmobranchii. Species in this subclass have skeletons made from cartilage, not bone, and have five to seven gill slits on each side of their heads (most other fish have only one gill slit on each side), which they use to filter oxygen from the water. Whale sharks, the largest fish s...
Sharks are found in deep and shallow waters throughout the world’s oceans, with some migrating vast distances to breed and feed. Some species are solitary, while others hang out in groups to varying degrees. Lemon sharks, for example, have been foundto congregate in groups to socialize. Scientists are still trying to figure out how long sharks live...
People aren’t on a shark’s menu. Even though shark attacks have increased at a steady ratesince 1900—a result of better recording of attacks and a rising human population—they are still exceedingly rare: A beachgoer has only a one in 11.5 million chance of being bitten. Sharks bite people out of curiosity, to defend themselves from a perceived thre...
Sharks may not be a significant threat to us, but we are to them. Humans are responsible for drastic declines in shark populations. Overfishing is the biggest threat. An estimated 100 million sharks are killed each year, mostly to supply demand for an expensive Chinese dish called shark fin soup. Some fisheries allow the catch of whole sharks, like...
- 5 min
25 lug 2019 · Sharks 101 | National Geographic. Sharks can rouse fear and awe like no other creature in the sea. Find out about the world's biggest and fastest sharks, how sharks reproduce, and how some...
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- National Geographic
learn about some of the 400+ species of sharks. All organisms have scientific names, a name that is unique for each species. Every species has two Latin names which allow people to be certain they are talking about the same creature no matter what language they speak.
With fossil records dating back 400 million years, sharks have outlived the dinosaurs and many other forms of life currently on earth. There are more than 1,000 species of sharks and rays, with new species discovered every year.
1 giorno fa · Shark, any of numerous species of cartilaginous fishes that make up the order Selachii (class Chondrichthyes). Most species have a tough skin that is dull gray in color and roughened by toothlike scales. The mouth contains sharp triangular teeth. Sharks lack a swim bladder and must swim to keep from sinking.
13 giu 2005 · A round-up of facts about one of the most iconic fishes. ByBrian Handwerk. June 13, 2005. •7 min read. The United States averages just 16 shark attacks each year and slightly less than one...
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