Unit 4: Adaptations for life in water

Question 1

How much of the earth is water

Answer 1

73%, as lakes, groundwater

Question 2

Challenges of living in water

Answer 2

1) Obtaining oxygen
2) Adjusting buoyancy
3) Maintaining body temperature
4) Maintnence of stable internal environment ( due to the movement of ions)

also…
1) sodium
2) temperature regimes

Question 3

what are two conditions that lead to high diversity

Answer 3

isolation and time

ex: freshwater lakes are inddependtnet if eahother so evolution of a species in one of these is independent of the other so tgey are isolarted and time means more braching of these species to make new ones

Question 4

How do they exchange o2 and co2

Answer 4

-from the gills
-not all do this but most; some can do cutaneous respeiration

Question 5

what is cutaneous respiration

Answer 5

-respiration across skin instead of gills
-adults frogs do this

Question 6

what are gills

Answer 6

delicate structures that project offof the gill arch

Question 7

Does gas exchange happen on the gills

Answer 7

sort of. It occurs more on the secondary lamerae, which is found in gill filaments.
-it goes gill arches, gill filaments, secondary filaments

Question 8

Where are gillls of teleosts found

Answer 8

-in the opercular cavities
-covered by operculum to prevent backflow

Question 9

What does the operculum do

Answer 9

it prevents backflow,

it covers the opercular cavities

Question 10

Unidirectional water flow

Answer 10

-the way water flows over gills, ventilates them like this

Question 11

Respiration is the exchange of gasses

Answer 11

YES

Question 12

WHAT ARE THE TWO VENTILLATION MECHANISMS

Answer 12

1) Bucal pumping
Buccal= cheek
-so cheek pumping
-mouth and opercular cavities pump water across the gills due to PRESSURE PRODUCED
-this occurs without movement of fish because this means that water can move over the gills without movement of water
so fish…
1. Takes a gulp of water
2. Close mouth
3. Push out the pharynx and conrtact muscles in throat to decrease throat volume/ volume in mouth
-this creates positive pressure that forces the water over the gills

2) Ram Ventillation
-fish swim with their mouth open to pass water over gills
-swimming and glow of water relative to the fish push it over the gills
-MORE PASSIVE
-some species are obligate ram ventillations so this means that they always need to be moving
-filter feeding and pelagic fish do this
-other fish may switch between this and bucal pumping when swiming

Question 13

Ventilation

Answer 13

pass water across gills so that gas exchange can occur

Question 14

what is more passive, bucal or ram ventillation?

Answer 14

Ram

Question 15

what types of fish do ram ventilation

Answer 15

pelagic and filter feeding fish

Question 16

Gas exchnage infprmation

Answer 16

-occurs in secondary lamellae
-passage of water opposes movement of blood: countercurrent exchange

Note:
-water and blood are not in direct contact, but capillaries for blood have thin membranes that allow gas exchange so o2 and co2 can diffuse across
-partial pressure gradient allows movement from high to low, ex: if blood has low o2 but water has high, o2 will move from h2o to blood
-the bigger the partial pressure difference, the faster it will diffuse

Question 17

Countercurrent exchange vs concurrent exchange

Answer 17

Countercurrent exchange:
water moves in one direction, blood moves in the other
-Very EFFICIENT
-get gas exchange through the lamella because of the gradient present
-look at pic

Concurrent:
water and blood are moving in the same direction
-not as big of a gradient throughout the whole lamella, so near the end both of them mau be almost equal (50,50) so NO NET MOVEMENT because remember there must be a pressure gradient

look at picture

Question 18

what is more efficient concurrent or countercurrent exchange

Answer 18

-countercurrent because opposite flow means more of a pressure gradient throughout

Question 19

How do fish get water out of air?

Answer 19

-some fish get o2 out of air, not just water, when o2 in water is low so they must get o2 another way
these are called Faculative or obligate air breathers ( common in ponds)
-Faculative also have potential to use other structures to gain it

1) Vascularized labyrinth organ
-vascularized chamber at the rear of head
-ex: siamese fighting fish

2) Lungs
ex: gars, lungfish, and tetrapods

Question 20

What changes buyancy

Answer 20

-air within the body
-mechanism used depends on the type of aquatic vertabrate

Question 21

What body parts can help with buyancy

Answer 21

lungs or gas bladder

Question 22

Swim bladders

Answer 22

-hollow structure that resists the exchange of gasses i.e gasses cannot be exchanged through this membrane
-the membrane is made of collagenous things so that it is impermeable to gasses
-bony fish use this

2 types:
1) PhysoSTOMOUS fish
Physo= bellow (chamber)
Stomous = mouth
-pneumatic air duct that connects stomach to gas bldader
-basically they come up to surface, take a gul[ of air, and pass it through the pneumatic duct to gas bladder and burp it out when wanting to adjusting buyoancy

2)Physoclistous fish
physo=bellow
clistous=closed
-NO PNEUMATIC AIR DUCT so no connection to move air from mouth to gas bladder but they have a RETA MIRABLE (means wonderful net)
-Reta mirable: site of gas exchange with gas bladder, it is a highly vascularized site so o2 from blood can cross so can increased or decrease are in gas bladder based on the amount/ concentration of oxygen in the blood

Question 23

Why do bony fish use swim bladders

Answer 23

they are neutrall buoyant due to swim bladders