Pisces and Class Chondrichthyes and Osteichthyes

Biology

definition

Osteichthyes

  • Skin with mucus gland. Paired fins made of rays and spines, or lobed fins lacking the rays and spines.
  • Various types of scales (ctenoid, ganoid, or cycloid).
  • Marine and fresh water species.
  • Gills used for respiration.
  • External fertilization: spawning, oviparous.
  • No external ears.
  • No eyes.
  • Skeleton made of bone.
  • Lateral line.
  • Two chambered heart. Operculum covering the gills. Brain with large optic lobes and cerebellum.
  • For example, Labeo, Hippocampus.

definition

Classification of Pisces

It is divided into three classes:
  • Class Placodermi (e.g., Climatius)
  • Class Chonrichthyes (e.g., Scoliodon, Torpedo, Chimaera)
  • Class Osteichthyes (e.g., Labeo, Hippocampus)

shortcut

Chondrichthyes

1. These fishes have teeth-like scales, denticles, which include the sharks, rays, skates and ratfishes.
2. Their mouth is usually located ventrally. 
3. These were the first fishes to have paired fins (pectoral and pelvic fins) for more efficient swimming.
4. They contain a cartilaginous endoskeleton, the deposits of calcium salts provide strength to them.
5. They have 5 to 7 gill slits per side and no swim bladder.
6. The notochord is present throughout life.
7. They are predatory fishes, they feed on other fishes, crustaceans and molluscs. They filter food particles like planktons from the water current that passes through the mouth, pharynx and gills
8. The heart is two-chambered, contains one auricle and one ventricle.
9. Male and females are separate and fertilization is internal. 

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