SHARK CLASSIFICATION

There are over 350 species of sharks known worldwide. Sharks are classified as follows: 

Kingdom Animalia
Phylum Chordata
SubPhylum Vertebrata
Class Chondrichthyes (cartilaginous fish)
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) 

Living sharks are divided into 8 Orders:

• Squatiniformes (flat body, mouth at front, no anal fin) - angelsharks, monkfish
• Pristiophoriformes (long snout, mouth underneath, no anal fin) - sawsharks
• Squaliformes (short snout, mouth underneath, no anal fin) - dogfish and cookiecutter sharks
• Carcharhiniformes (anal fin, 5 gill slits, 2 dorsal fins, no fin spines, mouth behind the eyes, nictitating eyelids) - ground sharks, including catsharks, swellsharks, shysharks, houndsharks, weasel sharks, requiem and hammerhead sharks
• Lamniformes (anal fin, 5 gill slits, 2 dorsal fins, no fin spines, mouth behind the eyes, no nictitating eyelids) - mackerel sharks, including the basking, goblin, megamouth, great white, crocodile shark, thresher, porbeagles, mackerel sharks, sandtiger, and mako sharks
• Orectolobiformes (anal fin, 5 gill slits, 2 dorsal fins, no fin spines, mouth in front of the eyes) - carpet sharks including the wobbegong, nurse, bamboosharks, blind, zebra, and whale shark
• Heterodontiformes (anal fin, 5 gill slits, 2 dorsal fins, dorsal fin spines) - bullhead, horn sharks
• Hexanchiformes (anal fin, 6-7 gills, 1 dorsal fin) - frilled and cow sharks - having six or seven gills on each side of the head.

---

CHARACTERISTICS OF THE EIGHT ORDERS OF SHARKS

No anal fin	Flattened body, mouth at the front.	.	SQUATINIFORMES (Angelsharks)
	Body not flattened, mouth underneath	Snout long and saw-like	PRISTIOPHOROFORMES (Sawsharks)
		Short snout	SQUALIFORMES (Dogfish sharks)

Anal fin present	5 gill slits, 2 dorsal fins	No fin spines	Mouth extends behind the eyes	Nictitating eyelids	CARCHARHINIFORMES (Requiem sharks and hammerheads)
				No nictitating eyelids	LAMNIFORMES (Mackerel sharks)
			Mouth ends in front of eyes	.	ORECTOLOBIFORMES (Carpet sharks)
		Has dorsal fin spines	.	.	HETERODONTIFORMES (Bullhead sharks)
	6 - 7 gill slits, 1 dorsal fin	.	.	.	HEXANCHIFORMES (6-Gilled and 7-Gilled sharks)

For further information log on website :
http://www.enchantedlearning.com/subjects/sharks/classification/index.shtml