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| | Classification of Sharks - The World of Sharks |
 | | Subclass Plagiostomi (sharks and rays: upper jaw hung from skulls and different kind of blood) |
 | | Superorder Selachimorpha (sharks: free upper eyelids, gill openings on the head, and pectoral fins separate from the side of the head) |
 | | Subclass Elasmobranchii (upper jaw that is not fused to the braincase, no swim bladder, advanced electroreceptive system, a spiracle, skin with placoid scales, teeth modified placoid scales, and 5-7 separate slit-like gill openings on each side of the body: there are about 600 species of sharks, skates, and rays) |
| www.worldofsharks.net /classification_sharks.htm (136 words) |
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