Hailey & Collin

A. Kingdom - Animalia, Phylum - Chordata,
Subphylum - Vertebrata, Infraphylum -
Gnathostomata, Class - Chondrichthyes
B. Carcharodon Carcharias (Great White)

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They're cartilaginous fish, have a skeleton of cartilage.
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Moveable jaws that typically have well developed teeth
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Mouth is almost always ventral, or under the head
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Paired lateral fins for efficient swimming
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Rough, sandpaper like skin, due to tiny placoid scales
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Include sharks, rays, skates, and chimaeras (also called ghost sharks)

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First appeared roughly 395 million years ago
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Sharks are can be referred to as "living fossils"
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Caudal fin, or tail fin, is well developed and very powerful
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Tail is usually heterocercal, meaning the upper lobe is longer than the lower lobe
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Ancestors had bone, developed into cartilage

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Require salt water or, with some species, freshwater
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A food source (fish, plankton, crustaceans, etc.)
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Most rays require warmer temperatures
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Most sharks require open waters

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Fertilization is internal
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Development is usually live birth
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However, some species lay eggs (oviparous)
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Some rare species are viviparous, meaning that the embryo develops inside the mother, eventually leading to live birth.
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Some Chondrichthyes guard their eggs, but there is no care for the young after birth

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Most sharks have tongues, but not all of them can move them
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Sharks do not have a swim bladder; instead they have a large liver filled with oil for buoyancy, with the exception of the Sandtiger Shark who swallows air to stay buoyant.
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The Spiny Dogfish may incubate its young for as long as two years

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http://en.wikipedia.org/wiki/Chondrichthyes http://vertebrates.voices.wooster.edu/chondrichthyes/ http://www.biodiversityexplorer.org/chondrichthyes/