Here is a quick thing on shark classification
Class- Chondrichtyes (cartilaginous fish)
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)
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)
Orders- Living sharks are split into 8 orders.