Osteichthyes-class

• Osteichthyes (bony fishes)

  • Includes both marine and fresh water fishes
  • Bony endoskeleton and streamlined body
  • Four pairs of gills covered by an operculum on each side
  • Skin is covered with cycloid/ctenoid scales
  • Mouth is mostly terminal
  • Air bladder is present which regulates buoyancy
  • Heart is two-chambered (1 auricle and 1 ventricle)
  • Cold-blooded animals
  • Sexes are separate
  • External fertilization
  • Mostly oviparous
  • Development is direct
• Marine Bony Fishes


  • Exocoetus (Flying fish)
• Examples for Freshwater Fishes

  • Labeo (Rohu)
  • Clarias (Magur)
  • Betta (Fighting fish)
  • Catla (Katla)
• Aquarium Fishes

  • Exocoetus (Flying fish)
  • Hippocampus (Sea horse)
  • Pterophyllum (Angel fish)
• Amphibia


  Gr. Amphi (both) + Bios (life) - animals that can live in both aquatic and terrestrial habitats
• Amphibians

  • Body is divisible into head, trunk and limbs
  • Tail may be present
  • Skin is moist and
  • Eyes have eyelids
  • A tympanum represents the ear
• Amphibians can live in both aquatic and terrestrial habitats
• Most amphibians have a moist skin and are cold-blooded
• Amphibians undergo metamorphosis during their life cycle
• Amphibians have a two-chambered heart
• Amphibians have a larval stage (tadpole) and an adult stage