Shark is a group of elasmobranch fish featured by cartilaginous skeleton, 5 to 6 gills slits on sides of head and pectoral fins are not fused to head. They are classified within clade Selachimorpha (or Selachii) and are sister group to rays. The word shark is used for extinct members of subclass Elasmobranchii such as … Continue reading The Shark fish: facts and nutrition