About Elasmobranch:

• The term elasmobranch refers to the sharks, rays, and skates.
• The other subclass of cartilaginous fish, the Holocephali, consists of Chimaeras – ratfish (Genus Chimaera) and elephant fish (Genus Callorhynchus).
• The main differences between these two subclasses are the structure of their gills and how they grow in the embryo.
  • Holocephali has four gill slits with a gill cover (an operculum), while Elasmobranchs have five to seven external gill slits with no gill cover.
• Characteristics of Elasmobranchs:
  • Its skeleton is made of cartilage rather than bone.
  • They have five to seven gill openings on each side.
  • Rigid dorsal fins (and spines if present)
  • Spiracles to aid in breathing
  • The upper jaw of elasmobranchs is not fused to their skull.
  • Elasmobranchs have several rows of teeth which are continually replaced.
  • They don’t have swim bladders, but instead their large livers are full of oil to provide buoyancy.
  • They reproduce sexually with internal fertilisation and either bear live young or lay eggs.
  • Elasmobranch skin is made of tiny, hard, tooth-like placoid scales called denticles.
  • These are renowned for their highly tuned senses, which make them incredibly successful in their environment.
• Their distribution ranges from near shore regions to the deep oceanic waters.
• Some species are known to travel long distances, hence can be considered as highly migratory. Their stock can be found in more than one Exclusive Economic Zone (EEZ).
• They are widely distributed in the Oceans but are most diverse in the tropical and subtropical Indo-Pacific Ocean.