Unit 4: Adaptations for life in water Flashcards
How much of the earth is water
73%, as lakes, groundwater
Challenges of living in water
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
what are two conditions that lead to high diversity
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
How do they exchange o2 and co2
-from the gills
-not all do this but most; some can do cutaneous respeiration
what is cutaneous respiration
-respiration across skin instead of gills
-adults frogs do this
what are gills
delicate structures that project offof the gill arch
Does gas exchange happen on the gills
sort of. It occurs more on the secondary lamerae, which is found in gill filaments.
-it goes gill arches, gill filaments, secondary filaments
Where are gillls of teleosts found
-in the opercular cavities
-covered by operculum to prevent backflow
What does the operculum do
it prevents backflow,
it covers the opercular cavities
Unidirectional water flow
-the way water flows over gills, ventilates them like this
Respiration is the exchange of gasses
YES
WHAT ARE THE TWO VENTILLATION MECHANISMS
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
Ventilation
pass water across gills so that gas exchange can occur
what is more passive, bucal or ram ventillation?
Ram
what types of fish do ram ventilation
pelagic and filter feeding fish
Gas exchnage infprmation
-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
Countercurrent exchange vs concurrent exchange
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
what is more efficient concurrent or countercurrent exchange
-countercurrent because opposite flow means more of a pressure gradient throughout
How do fish get water out of air?
-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
What changes buyancy
-air within the body
-mechanism used depends on the type of aquatic vertabrate
What body parts can help with buyancy
lungs or gas bladder
Swim bladders
-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
Why do bony fish use swim bladders
they are neutrall buoyant due to swim bladders
