About All Sharks

About All Sharks


BY. SHAUN LEVY


SHARK FAMILIES: There are more then 350 know species of sharks today, which can

all be placed under 8 scientific orders that contain 30 families.  They are

placed into these categories by their shared characteristics, this is called

taxonomy.  The more closeley related species are placed in another family in the

order.


SQUAINIFORMES: The angel shark as they are commonly known are

characterized by their RAY like flattened bodies.  This order has one family

which is called  SQUATINDAE that contains about 13 species.  The maximum size

that can be attained by any one of these species is 4-6 feet  in length.


PRISTIOPHORIFORMES: These shark are known as the saw shark.  This order has only

has one family


PHISTOPHORIFORMES which  contains five species.  These sharks are

easy to recongnize due to the fact that they posses an ellongated blade like

snout that is lined with sharp teeth along the edges, thus, the name saw sharks.


SQUALIFORMES: The order possesses three family which consist of about 82 species.

These sharks are characterized by their slender, cylinder-shaped bodies, long

snouts with shortened mouths.


HEXANCHIFORMES: The Hexanchiformes or cow sharks, comprise of two families.

Recognized by their six or seven pairs of gill slits, there sharks can often

be found in deep water.  The frilled shark (CHLAMYDISELACHUS ANGUINEUS)

who's appearance is quite unmistakable due to it's "eel" like appearance, is

perhaps one the strangest shark that exist today.


FOSSIL RECORD: Shark fossil record is fargmentery at best.  Most fossils found

so far consist of nothing but teeth in some cases a few vertebra  have been

found.  This is rare due to the fact that sharks have bones instead, they have

cartiladge which countrary common belief is rather solid.  In the rarest of

cases complete fossil have been discovered.  Scientific data shows that

following a period of great physiological changes.  There was not to many

changes in the sharks fossil in the millions of  years, of studying the shark

fossils. The Hybodonts who made their appearance some 320 million (years ago the

age of the dinosaurs) where quite common through out both oceanic and fresh

water.  Due to reasons unknown to science both oceanic and frThis is ONLY a preview of the article. If you would like to view the entire document, you must subscribe to Electronic References. Please register below now!


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