Life of Sea | Cow Shark | Cow shark, or Hexanchidae, is characterized by the shark family an extra pair or pairs of gill slits. There are currently four known species in three genera, Heptranchias, Hexanchus and Notorynchus. Cow sharks are considered the most primitive of all sharks, because their framework is similar to the shape of an ancient extinct, with few modern adaptations.
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.
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.