Air bladder anatomy
Problems with air Bladders
•
Pressure problems
– Boyles law – P1V1 = P2V2
– Slows speed at which you can change depths
-Phsyclistic
-Physostomus
Bohr and Root Effects
•
Accessibility to atmosphere
•
Increase size of fish
•
Secondary losses
Rete Mirabile – counter current exchanger
Bohr effect –
Root effect –
Other causes of shift:
-Increased temperature
-Salting out
1
Physoclistic Air Bladder Physiology
Bladder lined with guanine
crystals, impermeable to gas
Physostome Air Bladder Physiology
Gasses in bladder at high
pressure, exposure to capillary
bed will result in absorption
Gasses in bladder at high
pressure, exposure to capillary
bed will result in absorption
Atmosphere
Rete
Gas Gland
Blood supply
Vein
O2 CO2 release
regulated by
metabolic activity in
gas gland
Active secretion
Requires energy
Other uses for air bladders
•
Light reflection\
•
Sound production
•
Sound reception
Sphincter controls
gas exposure to oval
gland.
Vein
Artery
Capillary bed
Pneumatic
duct
Passive secretion
Regulated by exposure
to gland
Gas is pumped
into bladder
directly from
atmosphere
Sphincter controls
gas exposure to oval
gland.
Stomach
Respiration
•
•
Respiratory Surface
– Gills
– Stomach
– Lungs
– Cutaneous
• Body
• Buccal cavity
Moving water
– Buccal pump
– Ram ventilators
Dorsal View
Water
2
Gill anatomy
•
•
•
•
•
Filament
Arch
Rakers
Filament
Primary Lamellae
Secondary lamellae
Arch
Gill anatomy
Rakers
Secondary lamellae
Primary lamellae
Gill Surface area to body weight
•
Problems with too much
surface area
•
Problems with too little
surface area
Cutaneous Respiration
•
•
In water:
– aerial uptake (lungs)
– skin
– gills
In air:
– lungs
– skin
– gills (opercula closed)
40%
30%
30%
63%
37%
0%
1000
00
Polypteriformes
3
Air breathing fishes
•
•
•
•
Air breathing anatomy
Reduced gill surface area
Most freshwater – primarily swamps
– low pH and oxygen
Few marine
– Gobiidae
– Bleniidae
– Cottidae
374 species, 125 genera, 49 families, 17 orders
Obligate vs. facultative air breathers
•
•
Gill Raker Function
Obligate vs. Facultative air breather
Environmental adaptations to
– low oxygen conditions
– Predator refugia (swamps or deep water)
•
•
Raker spacing and size indicate feeding
mode
Large, widely spaced rakers
•
Small, fine rakers
15
14-15
14
13-14
12-13
11-12
13
12
10-11
9-10
8-9
11
10
7-8
6-7
9
5-6
4-5
8
7
6
5
35
t)
(p
p
30
27000
25
ity
20
al
in
15
18000
10
S
5
Temperature (C)
0
0
36000
4
9000
Dissolved Oxygen (mg/L)
High BOD in
some habitats
adds to
problems…
4
Skulls and Jaws
•
External representations of
major bones.
Evolution of Jaws
•
Earliest forms
– No jaws
– Cartilage cranium
– 8 Cartilage arches
support gill slits
•
Derived forms
– Jaws
– Bony cranium
– 5 arches support gills
•
Two theories
– Serial
Derived Fish Skull Components
•
Neurocranium –
•
Suspensocranium (suspensorium) –
•
Bronchial Skeleton –
– Composite
5