Excretory and digestive systems they are also unspecialised, suggesting that they may be similar to the primitive ancestor of sharks. Their most distinctive feature, however, is the sixth, and, in two genera, seventh, gill slits, in contrast to the five found in all other sharks.
Kingdom : Animalia
Phylum : Chordata
Class : Chondrichthyes
Subclass : Elasmobranchii
Order : Hexanchiformes
Family : Hexanchidae J. E. Gray, 1851
They range from 1.4 meters (4.6 feet) to more than 5.5 meters (18 feet) long adult body. Sharks are ovoviviparous cow, the mother retaining the egg-cases in her body until they hatch. They take a relatively large fish of all kinds, including other sharks, as well as on crustaceans and carrion.
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