1. Soft Anatomy Alimentary canal Gas bladder

2. Digestive tracts

3. Spiral valve intestine Chondricthyes Primitive Bony Fishes –Coelacanthiformes –Dipnoi –Polypteriformes –Acipenseriformes

4. Diet and intestinal length herbivorous piscivorous planktivorous

5. Gas Bladder General form: gas filled sac derived from the anterior portion of the alimentary tract Occurrence of the gas bladder in fishes Number of gas bladders -monopneumonan -dipneumonan Kind of gas bladder connections - physostomous -physoclistous

6. monopneumonan dipneumonan

7. physoclistous digestive tract gas bladder pneumatic duct physostomous

8. Primitive function: air breathing

9. Gas Bladder Functions 1.buoyancy control 2.respiration 3.sound production 4.sound reception

10. Structures associated with gas resorption and gas secretion Gas gland –gas secretion Oval –gas resorption Rete mirabile –Countercurrent gas exchange in blood

11. physostomous physoclistous

12. Addition of gas to the bladder Some physostomes are able to gulp air into the gas bladder

13. Addition of gas to the bladder Some physostomes are able to gulp air into the gas bladder Gas addition in both physostomes and physoclists via gas gland and rete mirabile –Processes involved are: blood acidification (Bohr and Root effects) “salting-out” effect countercurrent exchange (at rete mirabile)

14. Bhor and Root effects

15. Hemoglobin

16. Bhor and Root effects

17. “Salting out” effect Reduced gas solubility with increasing concentration of lactate and H + [lactate] + [H + ]Gas solubility

18. Countercurrent effect

21. Countercurrent exchange in the rete mirabile Gas gland

22. Metabolic processes for pumping gas into the gas bladder Rete mirabile Gas gland

23. Some pressure numbers

24. Physostomes can use Pneumatic duct Physoclists use highly vascularized Oval area –Oval isolated from main bladder Resorption of gas from bladder

25. benthic fishes without a gas bladder Gobiidae Percidae Bothidae

26. Charcharhinidae Blue shark Prionace glauca Pelagic sharks with high oil content Large livers containing low density lipids & squalene (hydrocarbon d=0.86)

27. Reduced density of musculature and skeletal tissues. Astronesthidae Astronesthes gemmnifer Many deepsea midwater fishes

28. Myctophidae Lanterfish Gonichthys sp. Diel Vertical Migrators (DVM) Degenerate bladder or lipid-filled bladder