General characteristic features of superclass Pisces (Fish)

  • They are the first jawed vertebrates and the study of fish is called Ichthyology.
  • They are aquatic (may be fresh water or marine).
  • Fish are cold blooded animals (poikilothermic).
  • Their body is spindle shaped or streamlined to enable them to move rapidly in water.
  • Body is covered with water proof dermal scales; which may be of placoid, cycloid, ctenoid or ganoid type.
  • Fins are the locomotary organs. Pectoral and pelvic fins are paired whereas dorsal and caudal fins are unpaired.
  • Eyes are without eyelids. External and middle ears are absent; only internal ear is present.
  • They consist of 4-7 pairs of gills for respiration which may be naked or covered with an operculum.
  • Heart is two chambered, known as a venous heart. Heart consists of only the impure blood.
  • Circulation of blood is uncircuit¬†with the presence of renal and hepatic portal systems.
  • RBCs are nucleated.
  • Endoskeleton is made up of either cartilage or true bones.
  • Vertebrae in fish are amphicoelus, in which centrum is concave at both the surfaces.
  • Skull is monocondylice with only one occipital condyle.
  • 10 pairs of cranial nerves are present.
  • They have a lateral line sense organ system consisting of rheoreceptors.
  • They may be ammonotelic or ureotelic with mesonephric¬†kidneys.
  • Fish are unisexual. Fertilization may be internal or external.
  • Eggs are of mesolecithal or megalecithal¬†type.

General characteristic features of superclass Pisces (Fish)