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Class osteichthyans


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Class osteichthyans

  1. 1. MilkfishChanos chanos
  2. 2.  Actinopterygii (Ray-finned fishes) Sarcopterygii (Lobe-finned fishes)
  3. 3.  Membranous fins are supported by slender fin rays radiating from basal skeletal elements within the body wall Gill slits covered by a bony operculum Air sac is usually present Internal nares are lacking Basal Actinopterygians Neopterygians
  4. 4.  Paleoniscoids  Large ganoid scales  Well-ossified endoskeleton  Air sacs are connected to the pharynx by an air duct that enebles aerial respiration Sturgeons and paddlefishes  Have endoskeleton is largely cartilaginous  Scales lack ganion  Skin of paddle-fishes is naked exept for small bony scales on tail
  5. 5.  Gras and bowfins  Trunk and tail of gars are covered with ganoid scales; trunk and tail of Amia have modern fish scales  Endoskeleton is ossified  Brainacase (neurocranium) remains largely cartilaginous Teleosts  “modern”  Scales are in the dermis, very thin and flexible  Dermal bones of the skull are thinner and more numerous  Jaws and palate are more independently maneuverable  Pelvic fins are far forward
  6. 6. - Fleshy lobe at the base of their paired fins- Have internal nares that open into the oropharyngeal cavity and retain a gas-filled air- Gill slits are covered by a bony opercullum that grows caudad from the second pharyngeal arch- Actinistia - coelacanths- Rhipidistia - Dipnoans
  7. 7. Lateral View
  8. 8. Tail fin (caudal fin)2 types of tail fin* Homocercal- Top and bottomhalves the same size.* Heterocercal- Top half differentsize than bottom half.
  9. 9. LATERAL LINE a. A system of canals on the sides of fishes that helps fish detect changes in pressure, vibrations and currents. b. This incredible sense organ helps fishes to detect prey, adjust their position to the currents, and keep in position in a school. c. They pick up vibrations from the swimming of other animals and water disturbed by sound waves, which cause changes in pressure. d. The longer the fish’s body the longer is the lateral line and the more sensitive to the environment. The canals are not only in the skin but also in the bone or cartilage of the head.
  10. 10.  Found on non-teleost bony fishes Usually diamond shaped bony scales “Heavy armor”
  11. 11.  Found on teleost fishes Light, thin, & flexible
  12. 12.  Teleost fishes Have comblike ridges along the exposed edge to reduce friction (drag)
  13. 13. a. Closed circulatory system i. The blood is always kept in vesselsb. Heart i. Only has two chambers ii. Blood goes from heart to gills tothe rest of the body iii. Mammals blood goes; heart,lungs, heart, rest of body