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Biology 4663: Advanced Elasmobranch Studies > Topic 4: Shark Physiology 3 > Flashcards

Topic 4: Shark Physiology 3 Flashcards

1
Q

What is the range of salinity for the open ocean?

A

34-35 aka 3.4-3.5% salinity

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2
Q

What is the break down of seawater? (9)

A
  • 96.5% water
  • 3.5% salts
    L> Chloride(Cl)= 55% (19.25g)
    L> Sodium(Na)= 30.6% (10.7g)
    L> Sulfate (SO4) = 7.7% (2.7g)
    L> Magnesium(Mg)= 3.7% (1.3g)
    L> Calcium(Ca)= 1.2% (0.42g)
    L> Potassium (K)= 1.1% (0.39g)
    L> Minor constituents= 0.7% (0.25g)
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3
Q

What are the two main salts in seawater?

A
  • Cl and Na
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4
Q

What are the three main electrolytes in seawater?

A
  • Cl, Na, K
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5
Q

How many shark species function in low salinity water?

A
  • 34
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6
Q

Why cannot a GW travel into freshwater?

A
  • bc it would die in a short order of time…cells would lyse ….can’t keep flow of water/maintain it!
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7
Q

What are the three umbrella terms for the groups that involved in osmoregulation?

A
  1. Organs
  2. Organic Compounds
  3. Inorganic ions
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8
Q

Osmoregulation Players:

1. What organs are involved?(4)

A
  1. Kidney
  2. Liver
  3. Gills
  4. Rectal gland
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9
Q

Osmoregulation Players:

2. What organic compounds are involved ? (2)

A
  1. Urea

2. TMAO ( trimethylamine oxide)

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10
Q

Osmoregulation Players:

3. What inorganic compounds are involved? (3)

A
  1. Sodium
  2. Chloride
  3. Other salts
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11
Q

Osmoregulation Players:

- Are the inorganic compounds (Na and Cl) always grouped together?

A
  • NO
  • Sodium is speared from the other salts in some areas of the gills and rectal glands to be utilized in sodium-potassium pumps!
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12
Q

What are the two sharks thought to have been involved in the real events that occurred in Jersey shore that Jaws was based off of? Issues??

A
  1. Bull shark
  2. Great White
    L> BUT GW would take on too much freshwater and couldn’t handle it. Although if there were high tides..salinity would be high enough for the great white to go up into freshwater swimming near the bottom through the seawater lingering there but it would have to leave the area with the tide!
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13
Q

Describe osmoregulation in a freshwater environment! (4)(teleost fish)

A
  • they drink little water
  • Actively takes up ions through the gills (water going in and ions too)
  • Absorbs water through skin (water in and ions out)
  • excretes very dilute urine and some ions
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14
Q

Describe osmoregulation in a marine environment! (teleost fish)

A
  • Drinks a lot of water
  • excretes ions and water through the gills
  • loses water through the skin but gains ions through the skin.
    -Excretes very concentrated urine! (with ions)
    L> ions present in it = Na+, K+ and Cl-
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15
Q

Marine fish are hyper osmotic or hypo osmotic?

A
  • Hypo osmotic
    L> they have a high water concentration in them so water and salt concentrations diffuse out of them via the process of osmosis.
    L> To make up for this they continuingly drink water and their gills process it, taking out the salt, to replace what they lost through osmosis. Because of these processes they have very little urine.
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16
Q

Freshwater fish are hyper osmotic or hypo osmotic?

A
  • hyper osmotic
    L>their insides are saltier than their surrounding environment (hyperosmotic). Osmosis draws water, salt, into its body via is skin and gills. As a consequence fresh water fish have very dilute urine and urinate often to balance off all the water coming from osmosis.
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17
Q

Elasmobranchs can be classified as ____ or ____. Hint: Think in terms of their waste product and a certain type of regulation…

A
  • Ureotelic: A ureotelic organism excretes excess nitrogen as urea
  • Ureosmotic: an organism (or species) that adjusts urea production or retention so as to maintain osmotic equilibrium, rather than as a means of disposing of surplus nitrogen.
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18
Q

Marine elasmobranchs surrounded by salt, gain or lose water? Why

A
  • lose water

- need to get rid of excess organic and inorganic compounds

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19
Q

Freshwater elasmobranchs are surrounded by freshwater, gain or lose salts and electrolytes? Why?

A
  • lose salts and electrolytes

- need to get rid of excess water

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20
Q

What does it mean to be a euryhaline species of elasmobranch?

A
  • their environments fluctuate in salinity
  • they must handle salt and fresh water conditions
  • *ability to adapt to a range of salinity
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21
Q

Many or few species of rays have become freshwater locked?

A
  • few
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22
Q

Where on an elasmobranch is osmolality maintained at or slightly above external osmolality?

A
  • body tissues
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23
Q

Explain osmolality in terms of a nurse shark in a marine environment.

A
  1. Gills:
    - Urea out
    - Water in
    - Salts out
    * *Body osmolality is maintained at 1000-1050mOsm/kg
    * * External seawater osmolality is ~1000 mOsm/kg
  2. Excretions from cloaca
    - Urea at 350mM
    - TMAO 60mM
    * * Urine Osmolality is 800 mOsm/kg
    * * Rectal Gland Osmolality is 940 mOsm/kg
    - **brings in salts from food
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24
Q

What is debated in terms of osmolality regulation in sharks?

A
  • whether or not the gills excrete urea …some people believe they are impermeable and the urea must leave via urine.
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25
Q

Sharks in general are slightly ____ to seawater. Fresh water diffuses into their bodies through the ___, ___ and other ___.

A
  • hyperosmotic
  • mouth
  • gills
  • exposed membranes
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26
Q

Describe basic intake of sharks in general.

A
  • food through mouth (water and salts transferred inwards)
  • Water and salts absorbed through gills
  • urea and TMAO in body tissue <retain a lot of TMAO but it is not specific to sharks
  • cloaca : excretes salt precipitate
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27
Q

To osmoregulate, use _____ and _____ by what organ?

A
  • Urea
  • Trimethylamine N-oxide (TMAO)
  • Liver
  • *put together via liver
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28
Q

Urea waste product is from what?

A
  • nitrogenous compounds…which can be toxic at high levels and will break down proteins
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29
Q

TMAO produces what kind of smell at low concentrations vs high concentrations?

A
  • Low: fishy smell

- High: strong ammonia smell

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30
Q

Describe some general characteristics of the interaction between TMAO and urea !

A
  • smell is from breakdown of proteins as well
  • higher levels of this than urea and it stabilizes urea
  • together urea and TMAO ensures the shark is saltier than the seawater (hyper osmotic )
    • TMAO counteracts urea to protect proteins
  • ** which came first? no one knows!
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31
Q

In polar fish they do depress what?

A
  • the freezing point via TMAO(acts like antifreeze) …thought to do the same in the greenland shark
    L> known to be very toxic meat when ingested
    **drunk like effects when consumed
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32
Q

What is the common name for Somniosus microcephalus ?

A
  • Greenland shark
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33
Q

What is the maximum length, average length and weight seen in greenland sharks?

A
  1. Max length: up to 7.3m (24`)
  2. Average length: 2.5m to 4.5m ( 8-15`)
  3. Weight: Up to 1,200kg ( 2,645lbs)
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34
Q

Where do Greenland sharks live?

A
  • deep, dark cold water
  • Arctic (salinity is decreased bc of run off from ice)
  • St. Lawrence as well
  • along Maine as well
  • *constantly changing in osmoregulation
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35
Q

The greenland shark has a ___ body. It has no ___fin. There is a distinct ____ on the caudal base. Its head is ___ compared to the rest of its body.

A
  • cylindrical
  • anal
  • caudal keel
  • smaller
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36
Q

Greenland shark:
-There are two large ___above and slightly behind the eyes. The shark’s skin can be __, __,__ or a spotted mix of all three. It’s whitened rostrum is a sign of what?

A
  • spiracles
  • black
  • brown
  • grey
  • repeated abrasion from the foraging shark’s quest for food on the seafloor.
  • *mostly collagen fibres
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37
Q

Greenland shark:

- It has __ dorsal fin(s) which are ___ and ___. The base of the dorsal(s) is ___ than the length.

A
  • 2
  • small
  • spineless
  • shorter than their lengths
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38
Q

Greenland shark:

- Its caudal fin is ____.

A
  • asymmetrical
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39
Q

Greenland shark:
- It’s eyes are ___ and ___ and are usually host to a _______, except in the case of the ___ specimens observed by GEERG which rarely have them.

A
  • round
  • small
  • parasitic copepod
  • St. Lawrence
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40
Q

Greenland shark:

- why do they have large nostrils?

A
  • compensate for the lack of vision!
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41
Q

Greenland shark:

- what happens to their eyes infected by the parasite?

A
  • clouds over the cornea like cataracts

- **relies a lot on chemo sense to smell prey

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42
Q

Greenland shark:

  • The sharks ____ determines its feeding technique.
A
  • dentition
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43
Q

Greenland shark:

  • The upper teeth are ___ but not ____ and enable the shark to ____ its food __. The bottom teeth, ___ and ___, serve to cut the food item by seining the head in a ____ motion. BY doing so, the shark cuts out?
A
  • pointy
  • serrated
  • pin
  • into position
  • wide
  • curved sideways
  • circular motion **jaws do not open wide
  • a round plug of flesh from its victim when it is too large to swallow whole.
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44
Q

Greenland shark:

- How many teeth are in the upper jaw? Lower jaw?

A
  • 48 to 52

- 50 to 52

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45
Q

Greenland shark:

- what happens to small prey?

A
  • if they are small enough to fit right into the sharks mouth, they are sucked off the bottom.
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46
Q

Greenland shark:

- describe its scales

A
  • they are dispersed all over the place….typical of a slow moving shark…since it doesn’t need to worry about laminar flow!
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47
Q

Greenland shark:

- what is a crucial factor for this shark’s comfort zone?

A
  • water temperature

- It prefers very cold water (-0.6 C to 10C)

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48
Q

Greenland shark:

- what determines whether it migrates up or down the water column?

A

-seasonal variations in water temperature determine its migration up or down the water column. (0-2200m)

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49
Q

Greenland shark:
- In the summer, the shark is normally found at ___ depth where the water is the ___. In the winter, it ___ which is colder than the water ____.

A
  • great
  • coldest
  • rises up to the surface layer
  • on the sea floor
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50
Q

Greenland shark:

- Aside from acting as an antifreeze what else do they believe TMAO does for these bottom dwelling sharks?

A
  • helps with pressure!
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51
Q

Greenland shark:
- Prey:
L> The greenland shark is a(n) _____ predator, primarily a ___.

A
  • an opportunistic predator

- scavenger

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52
Q

Greenland shark:
- Prey:
L> Verified Stomach contents?

A
  • Fish
  • mammals
  • invertebrates
  • others: birds and kelp
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53
Q

Greenland shark:
- Prey:
L> Verified Stomach contents:
- Fish??

A
  • Arctic charr, Atlantic Halibut, Atlantic salmon, capelin, cod, eelpout, eels, greenland halibut (turbot), grenadier, haddock, herring, lumpfish, pollack, sculpins, skates and other sharks including other greenland sharks (cannibalistic tendencies ), spotted wolffish
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54
Q

Greenland shark:
- Prey:
L> Verified Stomach contents?
- Mammals??

A
  • beluga, narwhal, porpoise, seals and other animals including a dog, horse, reindeer, lose and white polar bear remains.
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55
Q

Greenland shark:
- Prey:
L> Verified Stomach contents?
- Invertebrates??

A
  • crustaceans, gastropods, jellyfish, octopus, sea stars (sun stars and brittle stars), squid, urchins, whelk and other snails.
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56
Q

Greenland shark:
- Reproduction:
L> Has there been a lot of research?

A
  • hmm…nope
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57
Q

Greenland shark:
- Reproduction:
L> How does it have its young?

A
  • Ovoviviparous: its eggs develop and hatch within the female. The female gives both to at least 10 pups at a time each measuring approximately 40cm
58
Q

Greenland shark:
- Reproduction:
L> Have mating or birth been observed?

59
Q

Greenland shark:
- Reproduction:
L> Whom has been mostly observed to have mating scars and where?

A
  • females

- in the caudal area

60
Q

Greenland shark:
- Reproduction:
L> When the male decides to mate what does it do to the female?

A
  • it bites the female into submission but fortunately to the female its skin is twice as thick as the male’s
61
Q

Greenland shark:
- Reproduction:
L> What is the growth rate for the shark per year?

A

0.5 to 1.1cm per year

62
Q

Greenland shark:
- Reproduction:
L> A shark that was captured and tagged off Greenland in 1936 was recaptured in 1952. In 16 years how much had the sharks length increase?

A

only 8 cms

63
Q

Greenland shark:
- Reproduction:
L> Based on its growth rate what does this possibly make the greenland shark?

A
  • the longest living vertebrates on the planet
64
Q

Greenland shark:

- What is the only confirmed predator of them?

A
  • Sperm whale

L> Physeter Macrocephalus

65
Q

What wears down the teeth of sperm whales?

A
  • eating the dermal denticles! May rely on swallowing whole once they have been worn down enough
66
Q

Where does urea production occur?

67
Q

Where does retention of urea occur?

A

in the gills

68
Q

Where does reabsorption of urea occur?

69
Q

What does OUC stand for?

A

Ornithine urea cycle

70
Q

Ornithine urea cycle (OUC):

- What is a crucial enzyme needed for urea production?

A
  • Glutamine synthetase
71
Q

Ornithine urea cycle (OUC):

- In Euryhaline spp. there is a decrease/increase in the production of urea when entering fresh water.

72
Q

Ornithine urea cycle (OUC):

- Who lacks the enzyme needed for biosynthesis to occur?

A
  • Freshwater rays
73
Q

Ornithine urea cycle (OUC):

- Is urea produced in other areas?

A

UNSURE BRO

74
Q

Ornithine urea cycle (OUC):

- What is hypothesized to be responsible for the break down and production of urea?

75
Q

Glucose- Alanine cycle?

A
  1. In the muscles:
    - Glucose is broken down to pyruvate (using 2ATP)
    - 2pyruvate 2 lactate
    OR
    - 2 pyruvate Alanine (out: glutamate, alpha ketoglutarate)
  2. Liver:
    -Alanine (2) transported via blood to liver and is converted into pyruvate(2) and then Glucose to feed back to muscles
    **the conversion is via ALT and alpha ketoglutarate….out= glutamate which is converted into 2 NH3 which is converted into Urea
76
Q

Marine gills _____ urea.

77
Q

Marine Gills retain urea:

- Do they lose much urea across the gills?

78
Q

Marine Gills retain urea:

- What prevents loss of urea through the gills?

A
  • their basolateral membrane which has a high cholesterol to phospholipid ratio levels which limits diffusion (urea can’t get through )
79
Q

Marine Gills retain urea:

- Active or passive transport of urea occurs here?

A
  • Active transport of urea by Na+/ urea anti-porter energized by Na+/K+ ATPase
80
Q

Marine Gills retain urea:

- Urea is used more for ____ and ____.

A
  • salt regulation

- acid base balance

81
Q

Explain elasmobranch urea retention!

A
  • 2K + ions move through the basolateral membrane via NKA transporter
  • Na+ passes through the basolateral side….
  • 3Na+ moves back into the inner part of the basolateral membrane via an unknown transporter which is coupled with the transport of Urea out through the basolateral side which is than transported in the blood!
82
Q

Kidneys Reabsorb Urea:

- Reabsorption contributes to high/low urea levels? Up to __%

A
  • high

- 96% ** 4% is lost via urine

83
Q

Kidneys Reabsorb Urea:

- Is there a site of urea loss at all?

A
  • a minor one
84
Q

Kidneys Reabsorb Urea:

- What type of transport is this thought to involve?

A
  • active transport
85
Q

Kidneys Reabsorb Urea:

- What kind of pump does this use?

A
  • urea-sodium pump
86
Q

Kidneys Reabsorb Urea:

- What is the second hypothesis proposed for transport?

A
  • passive transport but it hasn’t been proven
87
Q

Kidneys Reabsorb Urea:

- Describe what is going on with Euryhaline spp. for when they enter areas of decreased salinity.

A
  • they decrease renal reabsorption of urea as they enter areas of decreased salinity
    L> increases rate of urine flow to rid system of excess urea
88
Q

Kidneys Reabsorb Urea:

- What is special about a sharks kidney?

A
  • they have four loops to increase surface area for reabsorption (two pairs) vs mammalian kidney which only has one loop
89
Q

Kidneys Reabsorb Urea:
- What is the affect of varying salinity levels on the amount of transporters present in the cells that move urea from cells into blood?

A
  1. High salinity : lots of transporters
  2. low salinity: few transporters -> aka decreased movement of urea..(freshwater) voiding it into urine instead of retaining it.
  3. High salinity: lots of transporters
90
Q

Salt Regulation:
- Gills:
L> With salt uptake when are Na+/K+ ATPase even higher?

A
  • when in freshwater
91
Q

Salt Regulation:
-Gills:
L> Acid Base balance?

A
  • secrete acid
  • H+ excreted/exchanged for Na+
  • Run by Na+/K+ ATPases
92
Q

Salt Regulation:
- Gills:
L> Responsible for ___ secretion

93
Q

Salt Regulation:
- Kidney Salt excretion:
L>In a dilute environment, urine flow increases/decreases

94
Q

Salt Regulation:
- Kidney Salt excretion:
L> In a saltwater environment are the kidneys solely responsible for salt secretion?

A

no

L> rectal gland is responsible for a lot of salt excretion

95
Q

Salt Regulation:
- Kidney Salt excretion:
L> Summarize osmoregulation of saltwater elasmobranch

A
  • Gills block loss of urea and TMAO
  • water is absorbed by gills and skin
  • Ingests salts with food
  • salts lost via feces
  • most urea and TMAO retained by kidney
  • sodium excreted by rectal gland
  • divalent ions excreted in urine
  • Body fluids: 1100mOsmo/kg
  • seawater/medium: 1000mOsm/kg
96
Q

Salt Regulation:
- Rectal Gland:
L> Marine elasmobranchs face what problem?

A
  • the problem of continuous diffusion of salts into the body from the sea water
97
Q

Salt Regulation:
- Rectal Gland:
L> What does the rectal glad function in?

A
  • a salt excreting mechanism

L> excretes a milky like substance which is in high concentration of salts with a tiny bit of water to help remove it.

98
Q

Salt Regulation:
- Rectal Gland:
L> What happens to the rectal gland of a bull shark moving into freshwater?(Euryhaline spp)

A
  • it becomes regressive….(atrophy )
99
Q

Salt Regulation:
- Rectal Gland:
L> Is there a functional one in freshwater rays?

100
Q

Salt Regulation:
- Rectal Gland:
L> How are salts eliminated?

A
  • moved from blood into cells of rectal gland via active transport probably
101
Q

Osmoregulation:

- Bull sharks can move where?

A
  • from marine water up into freshwater
102
Q

Osmoregulation:
- Bull sharks in freshwater have a total osmotic pressure about / that of marine values. There is also a 20% reduction of __ and ___ and a more than 50% reduction of __.

A
  • 2/3’s
  • bodily sodium and chloride
  • urea
103
Q

Osmoregulation:
- Bull sharks still had body fluids more than ___ as salty as typical freshwater fishes. And copious excretion of ____ which is ____.

A
  • twice (therefore getting twice the water intake)
  • dilute urine
  • energetically expensive
104
Q

Osmoregulation:
- Urea, TMAO and other Ions:
L> In marine forms, plasma osmolarity is ___, in many cases ____ than surrounding seawater due to ___ and ___.

A
  • high
  • higher
  • urea
  • TMAO
105
Q

Osmoregulation:
- Urea, TMAO and other Ions:
L> Bull sharks had serum urea levels of __ mM/1 and TMAO levels of ___mM/1.

A
  • 356

- 46.6

106
Q

Osmoregulation:
- Urea, TMAO and other Ions:
L> In marine elasmobranchs what is kept below sea water?

A
  • inorganic ions such as sodium and chloride
107
Q

Osmoregulation:
- Levels from bull sharks taken from fresh and estuarine waters, mean serum urea levels were __mM/1 and TMAO levels were ___mM/1.

A
  • 169

- 13.2

108
Q

Osmoregulation:

- Sodium and chloride levels are ___ than in marine elasmobranchs

109
Q

Osmoregulation:
- Bull sharks in fresh water had urea levels __% less than marine bull sharks, magnesium levels __% lower and sodium and chloride levels about __% less.

A
  • ~40%
  • ~37%
  • 80%
110
Q

-What is the common name for Carcharhinus Leucas?

A

Bull shark

111
Q

The bull shark can be up to __cm (__ft) in length at birth. Adult female bull sharks average __m(__ft) long and typically weigh __kg(__lbs). Adult males are slightly __ than females and average __m(__ft) and __kg (__lbs).

A
  • 81cm –> 2.66ft
  • 2.4m –> 7.9ft
  • 130kg –> 290lbs
  • 2.25m –> 7.4ft
  • 95kg —> 209lbs
112
Q

What shark has the strongest bite force rivalling the great white?

A 
- bull shark 
L> teeth are smaller 
L> broader head 
L> thicker muscles in jaw vs typical shark....increasing bite force 
- bite force is spread out
113
Q

Can bull sharks thermoregulate well?

114
Q

Are bull sharks very aggressive? Picky eaters?

A
  • very aggressive –> high testosterone levels but not the highest in the animal kingdom
  • they eat just about anything
115
Q

Serum levels of uterine pups of bull sharks resemble those of ?

A

mothers in euryhaline environment!
L> change as the mother pass from fresh to saltwater and back
**Juveniles can match adults but pups it takes longer

116
Q

When and where do bull sharks mate?

A
  • They mate during late summer and early autumn

- often in the brackish(mixture of salt and fresh) water of river mouths

117
Q

Bullshark:
- After gestating for __ months, a bull shark may give birth to __ to__ live young. They are ___; they are born live and free swimming.

A
  • 12
  • 4
  • 10
  • viviparous
118
Q

Bullshark:

- The young are about _cm (_in) at birth and take _ years to reach maturity.

A
  • 70cm
  • 27.6 in
  • 10 years
119
Q

Bullshark:

- Where are common nursery habitats for them?

A
  • costal lagoons, river mouths, and other low salinity estuaries
    L> these areas are chosen because there would be less predators to go after young…..and less energy will be wasted on osmoregulation allowing them to focus on growing
    L> also lots of easy prey!
120
Q

Bullshark:

- Can they be kept in captivity?

A
  • no

- estimates 25-30 years

121
Q

Endocrine Regulation to Regulate Body Fluid Volume and Solute Concentration:
- What three hormones?

A
  • CNP
  • AVT
  • RAS
122
Q

Endocrine Regulation to Regulate Body Fluid Volume and Solute Concentration:
- What does CNP stand for?Released from? Function?

A
  • C-type Natriuretic peptide
    L> released from heart
    L> stimulates salt secretion from rectal gland
    L> inhibit drinking and relax blood vessels (more open)–>whisking water from tissue
    L> binds to kidney…increasing urin production, increasing salt excretion.
    **released when issue with H2O influx
123
Q

Endocrine Regulation to Regulate Body Fluid Volume and Solute Concentration:
- What does AVT stand for? Released from? Function?

A
  • Argininevasotocin
    L> penile gland produces this in the brain
    L> increases in plasma osmolality
    L> reduces urine production
    L> retains more water
    L> opposite of CNP ….BUT has nothing to do with drinking or blood.
124
Q

Endocrine Regulation to Regulate Body Fluid Volume and Solute Concentration:
- What does RAS stand for? Released from? Function?

A

-Renin Angiotensin System
L>Antagonistic to CNP, reduces urine flow
L> Increases drinking
L> constricts blood vessels (constricting blood flow into kidney area
L> produced by kidneys

125
Q

Body fluid of euryhaline elasmobranchs:

- They are ____ in freshwater.

A
  • ammonotelic : produces soluble ammonium
126
Q

Body fluid of euryhaline elasmobranchs:

- As salinity increases what happens?(4)

A
  1. increase urea production and retention
  2. Decrease urea excretion
  3. Increase Na+ and Ca+
  4. Decrease ammonia excretion
127
Q

Body fluid of euryhaline elasmobranchs:

- Can they produce and retain as much urea as strictly marine spp.?

A
  • nope

- they have lower osmolality

128
Q

Body fluid of euryhaline elasmobranchs:

- As salinity decreases what happens?

A
  1. Lower osmolality (less urea and TMAO) than marine spp.
  2. Decrease amount of urea produced and reabsorbed
  3. Increased urinary excretion
  4. Loss of sodium and chloride balanced by electrolyte uptake at the gills and reabsorbed by the kidneys
129
Q

Freshwater Elasmobranchs Body Fluid:

- They have lost the ability to synthesize and retain ___ or ___.

A
  • urea, TMAO <– no need for them in FW
130
Q

Body fluid of euryhaline elasmobranchs:

- Body fluid solute concentrations are relatively high/low

131
Q

Body fluid of euryhaline elasmobranchs:

- Freshwater rays have abandoned what?

A
  • renal absorption
    L> urine is dilute –>constantly getting freshwater intake
  • Ammonotelic
132
Q

Potamotrygonidae are?

A
  • well studied rays!
133
Q

Potamotrygonidae:

-Stingrays that have an osmotic physiology that is distinctly similar or different from all other elasmobranchs ?

134
Q

Potamotrygonidae:
- Their blood solute concentration measures about half that of ___ tolerant elasmobranchs and roughly equals of freshwater teleosts.

A

-freshwater

135
Q

Potamotrygonidae:

- Moreover the body fluid of these river stingrays have be very ___ levels of urea.

136
Q
  • Do they have a rectal gland? (rays)
A

While they do some have rectal glands, this organ is greatly reduced in size and apparently does not excrete salts.

137
Q

Potamotrygonidae:

- Freshwater stingrays of south america have been abandoned retention of___lack a functional ___ and they osmoregulate.

A
  • urea

- lack a functional rectal gland

138
Q

Potamotrygonidae:

-Do they osmoregulate as much as freshwater teleost!

139
Q

Potamotrygonidae:
- Their ancestors were __ and most likely trapped _______when the tectonic uplift of the Andes Mountains occurred in the early to middle Cretaceous period

A
  • marine
  • on the shallow western side of south America
  • C period: 100 million years ago!
140
Q

Potamotrygonidae:
- By the close of the cretaceous period ( about _ million ) Their isolation and freshening of their waters by runoff were complete

A
  • 65 million years ago

Biology 4663: Advanced Elasmobranch Studies (11 decks)

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