Sharks - Questions and Answers About Sharks

Learn About These Fascinating Elasmobranchs

There are about 400 species of sharks. Learn about sharks through some questions and answers about these fascinating marine animals.

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Shark Grey reef shark and diver, Yap Island
Alexander Safonov/Moment/Getty Images

Sharks are classified in the Phylum Chordata (the same phylum as humnas), Subphylum Vertebrata, and Class Elasmobranchii. All elasmobranchs are cartilaginous fish, which means their skeleton is made out of cartilage, rather than bone. Learn more about characteristics of sharks, including their anatomy, how many species of sharks there are, and where sharks live.

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Kitefin Shark Skeleton / Ryan Somma, Flickr
Kitefin shark skeleton. Courtesy Ryan Somma, Flickr

Elasmobranchs are mentioned above, but here you can learn more about the characteristics of elasmobranchs, how they differ from bony fish, and what other animals are also classified as elasmobranchs. Click here to learn more about elasmobranchs.

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Whale Shark / Laszlo-Photo, Flickr
Whale Shark (Rhincodon typus), Coiba National Park, Panama. Courtesy laszlo-photo, Flickr

The largest shark in the world is the whale shark (Rhincodon typus), which is believed to reach a maximum length of about 60 feet. Despite their huge size, whale sharks feed on some of the smallest animals in the ocean and are relatively docile. The smallest shark is thought to be the dwarf lanternshark (Etmopterus perryi) which is about 6-8 inches long. Learn more about the largest shark.

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Shortfin Mako Shark / NOAA
Shortfin Mako Shark (Isurus oxyrinchus). NOAA

How fast can a shark swim, and what is the fastest shark species? The fastest shark species is the shortfin mako shark, although there is some debate over how fast they can swim, and whether they are the world's fastest fish. Learn more about how fast sharks swim.

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Tiger Shark / Armando F. Jenik, Getty Images
Tiger Shark in the Caribbean. Armando F. Jenik / Getty Images

Of the hundreds of shark species, by far there are 3 species most likely to attack. These are the white (also called the great white), tiger and bull sharks. Learn more about these species here and about how many humans they have attacked.

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Shark Egg Case Image / Sander van der Wel/Flickr
Shark egg case, with shark embryo visible, Rotterdam Zoo. Sander van der Wel, Flickr

Unlike us mammals, who only give birth to live young, sharks have a wide range of strategies to make sure their young survive from conception until birth. Some sharks lay eggs, and some give birth to live young - some species even nourish their young with a placenta. Here you can learn more about the reproductive strategies of sharks, and examples of species that employ different types of nourishing their young and giving birth.

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Shark finning is a brutal practice in which sharks are hunted for their fins, which are a popular delicacy in some areas, and in some cases the fins are sliced off while the rest of the (live) shark is thrown back into the ocean. There has been recent progress in limiting this practice, but it still continues in some areas.

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Will you be swimming in an area where sharks may be present? There are some simple, common-sense precautions you can take to help avoid a shark attack. Learn more about preventing a shark attack here.

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Basking shark image showing head, gills and dorsal fin
Basking shark (Cetorhinus maximus), showing head, gills and dorsal fin. © Dianna Schulte, Blue Ocean Society

For many years, scientists thought basking sharks hibernated on the ocean bottom. But some research in Massachusetts showed that at least for some sharks, that was not at all the case. Learn more about where basking sharks migrate.