Soft Anatomy • Alimentary canal • Gas bladder
Jan 16, 2016
Soft Anatomy
• Alimentary canal
• Gas bladder
Digestive tracts
Spiral valve intestine
• Chondricthyes• Primitive Bony
Fishes– Coelacanthiformes– Dipnoi– Polypteriformes– Acipenseriformes
Diet and intestinal length
herbivorous
piscivorous
planktivorous
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
physoclistous
digestive tract
gas bladder
pneumatic duct
physostomous
Primitive function: air breathing
Gas Bladder Functions
1. buoyancy control2. respiration3. sound production4. 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 and 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 g
lan
d
Metabolic processes for pumping gas into the gas bladder
Rete mirabile
Gas gland
Some pressure numbers
• Physostomes can use Pneumatic
duct• Physoclists use highly vascularized
Oval area – Oval isolated from main bladder
Resorption of gas from bladder
benthic fishes without a gas bladder
Gobiidae
Percidae
Bothidae
Charcharhinidae Blue sharkPrionace glauca
Pelagic sharks with high oil content
Large livers containing low density lipids & squalene (hydrocarbon d=0.86)
Reduced density of musculature and skeletal tissues.
AstronesthidaeAstronesthes gemmnifer
Many deepsea midwater fishes
MyctophidaeLanterfishGonichthys sp.
Diel Vertical Migrators (DVM)
Degenerate bladder or lipid-filled bladder