Osteichthyes

1. Osteichthyes The Bony Fish

2. Class Osteichthyes Characterized by having: • Bone in their skeleton • An operculum covering the gill openings • A swimbladder or lungs • True scales • Paired fins • Homocercal tail (Exception lungfish – diphycercal) • Mouth terminal • Two chambered heart • Sexes separate (Sex reversal in some) • Fertilization external for most • Excrete ammonia

3. Class Osteichthyes The bony fishes are the most diverse class of fish. ~24,000 species Osteichthyes are divided into two subclasses • The lobe-finned fish (Sarcopterygians) • The ray-finned fish (Actinopterygians). *Most modern fish are members of the ray-finned, Teleost subdivision.

6. Sarcopterygians • Sarcopterygians are the fish most closely related to modern amphibians, reptiles, birds, and mammals • This subclass includes the lungfish and coelacanth. Coelacanth were thought to have become extinct at about the same time as the dinosaurs, until a live specimen was found in 1938

7. Sarcopterygians • Characteristics: • Muscular lobe associated with fins • Have lungs for gas exchange • Live in areas with seasonal droughts • Can breathe air if water stagnates • Cannot withstand desiccation • Burrow in the mud • Have enamel on the teeth

8. Sarcopterygians • Can survive drought by remaining in aestivation for 6 months or more • Aestivation = dormant state • After rain fills the lake or riverbed Lungfish emerge from their burrows to feed & reproduce

10. Lungfish - Found in Australia & Madagascar

11. Lungfish scales • Cosmoid scales

12. Lungfish Circulation

13. Coelacanth

14. Actinopterygians • Ray-finned fish (Fins lack muscular lobes) • Have swimbldders to regulate buoyancy • ~23,900 species

15. Chondrosteans (Fresh water fish) • Include stergeons and paddlefish • Stergeon eggs make caviar

16. Caviar = Sturgeon eggs

17. Paddlefish

18. Subdivisions of Teleostei • Superorder Ostariophysi • Order Cypriniformes (minnows, carps) • Order Siluriformes (catfish) • Superorder Protacanthopterygii • Order Esociformes (pikes) • Order Osmeriformes (smelts) • Order Salmoniformes (salmon, trout, whitefish) • Superorder Paracanthopterygii • Order Gadiformes (cod, hakes, pollock) • Superorder Acanthopterygii • Order Percoidei (perches, snook, basses) • Order Pleuronectiformes (flounders, soles) • Order Perciformes (mackerel, tuna, swordfish)

19. Actinopterygians TheTeleosts • Teleosts are modern day ray-finned fish • Use their fins and body wall to push against water for locomotion • Some secrete mucus to reduce friction • Most teleosts are carnivores swallowing prey whole • Herring & paddlefish are filter feeders • Teleosts have pyloric ceca (outpockets in the small intestine to increase absorption)

20. Ganoid Fish Scales • Found on non-teleost bony fishes • Usually diamond shaped bony scales • “Heavy armor”

21. Cycloid Fish scales • Found on teleost fishes • Light, thin, & flexible

22. Ctenoid Fish Scales • Teleost fishes • Have comblike ridges along the exposed edge to reduce friction (drag)

23. Myomeres

25. Swimming mechanics • Thrust- force in animal's direction  • Lift- force opposite in right angles to the thrust  • Drag- force opposite the direction of movement

26. Swimming mechanics • Yaw – side to side movement of head • Pitch – up and down movement of head