Physiology

Question 1

Specific gravity

Answer 1

ration of density of an object to reference substance

Question 2

Methods for reducing sinking rate

Answer 2

Low-density compounds, Lipids: lighter than water
and Reduce the amount salt water in body

Lifting surface: epicercal and homocercal tail, pectoral fins

Reduction in bone and muscle

Cartilage (sp g = 1.1) rather than bone (sp g = 2)

Swim bladder: precise control of neutral buoyancy

Question 3

Swim bladder

Answer 3

Precise control over neutral buoyancy
Can occupy 5% of volume in marine waters
Occupy 7% of volume in freshwater

Question 4

Formation of swim bladder

Answer 4

Outcropping of the gut to form lung
This began below the gut
Eventually moved above gut
In its most derived state it is disconnected from the gut

Question 5

How does a swim bladder work?

Answer 5

Impermeable flexible wall, lined with guanine crystals
Rete mirabile inflates the bladder
Oval reabsorbs the oxygen
Sugar diffuses into gas gland, and breaks it down
Passes H+ back into blood – making blood more acidic
Hemoglobin releases oxygen and this diffuse into the swim bladder along with N2
The oval will reabsorb O2 and N2 to deflate

Question 6

Deep sea swim bladder concentration

Answer 6

75% O2

Question 7

Surface water swim bladder concentration

Answer 7

99% N2

Question 8

Swim bladder portable supply of oxygen

Answer 8

10 m depth, 20 min supply
1000m depth 210 hours supply

Question 9

Seawater osmoles

Answer 9

~1050
Hagfish and molluscs (~1050) isosmotic
Sharks (~1100) slightly hyperosmotic
Marine and deep sea teleost (~450-500) hyposmotic
Coelacanth (~1050) isomostic

Question 10

Freshwater osmoles

Answer 10

1-10
FW Teleost 275
Lungfish 240
Polypterus 200
Lamprey 270
FW Sharks 465
Amphibian 220
Birds 320
Mammals 300
All are hyperosmotic

Question 11

Marine Fish Osmoregulation

Answer 11

Marine fish drink lots of water (25% of body weight a day)
low skin permeability, pump out salt
Isosmotic urine, tendency to dehydrate

Question 12

FW Fish Osmoregulation

Answer 12

Need to recover salts through prey
can sometimes absorb salts through gills
Dilute urine, tendency towards hydration

Question 13

Salmonids FW to SW

Answer 13

Increase in growth hormone (GH), cortisol and thyroxine production promotes chloride secretion cells in gills and osmoregulatroy processes
This is to deal with loss of body water

Question 14

Salmonids SW to FW

Answer 14

Increase productio of prolactin, minimize sodium loss across gills

Question 15

Effects of the stress on salmonids

Answer 15

Stress increase epinephrine, this causes increase gill permeability leading to osmotic shock
Often add salts to transport water to help fish survive, Calcium also reduces stress

Question 16

Freezing Resistance

Answer 16

Seawater freezes at -1.86 degrees celcius
Hypoosmotic fish can freeze completely in unfrozen water
Hyperosmotic fish cannot freeze until the water has frozen
Most marine fish freeze at -0.8 degree celsius
Arctic fish have glycoproteins in tissues (repeated alanine units and sugars)
300 times more effective at reducing freezing than equivalent concentration of ions