Soft Anatomy Alimentary canal Gas bladder Digestive tracts
Soft Anatomy • Alimentary canal • Gas bladder
Digestive tracts
Spiral valve intestine • Chondricthyes • Primitive Bony Fishes – – Coelacanthiformes Dipnoi Polypteriformes Acipenseriformes
Diet and intestinal length herbivorous planktivorous piscivorous
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
monopneumonan dipneumonan
pneumatic duct physostomous gas bladder physoclistous digestive tract
Primitive function: air breathing
Gas Bladder Functions 1. 2. 3. 4. buoyancy control respiration sound production sound reception
Structures associated with gas resorption and gas secretion • Gas gland – gas secretion • Oval – gas resorption • Rete mirabile – Countercurrent gas exchange in blood
physostomous physoclistous
Addition of gas to the bladder • Some physostomes are able to gulp air into the gas bladder
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 rete mirabile – Processes involved are: • blood acidification (Bohr and Root effects) • “salting-out” effect • countercurrent exchange (at rete mirabile)
Bhor and Root effects
Hemoglobin
Bhor and Root effects
“Salting out” effect • Reduced gas solubility with increasing concentration of lactate and H+ [lactate] + [H+] Gas solubility
Countercurrent effect
Countercurrent exchange in the rete mirabile Gas gland
Metabolic processes for pumping gas into the gas bladder Gas gland Rete mirabile
Some pressure numbers
Resorption of gas from bladder • Physostomes can use Pneumatic duct • Physoclists use highly vascularized Oval area – Oval isolated from main bladder
benthic fishes without a gas bladder Percidae Bothidae Gobiidae
Pelagic sharks with high oil content Charcharhinidae Blue shark Prionace glauca Large livers containing low density lipids & squalene (hydrocarbon d=0. 86)
Many deepsea midwater fishes Astronesthidae Astronesthes gemmnifer Reduced density of musculature and skeletal tissues.
Diel Vertical Migrators (DVM) Degenerate bladder or lipid-filled bladder Myctophidae Lanterfish Gonichthys sp.
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