TOPIC 4 (UNIT 2)

Question 1

challenges to living in water

Answer 1

1. obtaining oxygen
2. adjusting buoyancy
3. maintain body temperature
4. maintenance of a stable internal environment due to movement of water and ions

Question 2

why are freshwater species more diverse than seawater

Answer 2

1. isolation
2. time

Question 3

ectothermic

Answer 3

regulate temperature through external means (ex. swim to surface to warm up, swim to cooler area to cool down)

ecto -> outside
thermic -> temperature

Question 4

adaptation

Answer 4

evolutionary solution to a species’ ecological situation due to natural selection

Question 5

teleosts

Answer 5

fish

Question 6

how do most aquatic vertebrates respire?

Answer 6

exchange oxygen and carbon dioxide from body via gills

Question 7

how do amphibians respire

Answer 7

cutaneous respiration (breathes through skin)

Question 8

where are the gills of teleosts located

Answer 8

in opercular cavities (behind flap at head)

covered by operculum to prevent backflow

unidirectional water flow

Question 9

gill arch

Answer 9

developed on cell/tissue level to optimize respiration

Question 10

gill filaments

Answer 10

provide ventilation

Question 11

gills

Answer 11

delicate structures that project off gill arch

gas exchange occurs on secondary lamellae

Question 12

operculum vs gill arch vs gill filaments

Answer 12

operculum -> flap itself
gill arch -> skin attachment separating operculum from gills
gill filaments -> stripey flesh coloured portion under operculum

Question 13

2 ways fish are able to ventilate

Answer 13

buccal pumping

ram ventilation

Question 14

fish ventilation

Answer 14

pass water across gills so gas exchange can occur

Question 15

buccal pumping

Answer 15

method of fish ventilation:

mouth and opercular cavities pump water across gills due to positive pressure produced

Question 16

ram ventilation

Answer 16

method of fish ventilation:

fish swims with their mouth open to pass water across gills

• many pelagic and filter feeding fish do this
• others may switch when actively swimming

Question 17

where does gas exchange occur in fish

Answer 17

occurs in secondary lamellae of gill

Question 18

countercurrent exchange

Answer 18

passage of water opposes movement of blood in gills

Question 19

how do fishes get O2

Answer 19

most use gills to extract O2 from water

Question 20

how have aquatic species evolved to obtain O2 an alternative way

Answer 20

facultative/obligate air breathers

use a vascularized labyrinth organ - vascularized chamber at the rear of head

others have lungs (ex. gars, lungfish, tetrapods)

Question 21

air within the body of an aquatic vertebrate changes its __________

Answer 21

buoyancy

Question 22

how is buoyancy changed in an aquatic vertebrate

Answer 22

air in the body

ex. lungs, swim bladders

Question 23

bony fish are buoyant due to _________

Answer 23

swim bladders

Question 24

physostomous vs physoclistous

Answer 24

both are bony fishes with varying swim bladders

physostomous:
- retain a duct (pneumatic duct) allowing them to fill the bladder by gulping air

physoclistous
- lack pneumatic duct, using blood vessels (rete mirabile) to regulate gas

Question 25

how do cartilaginous fish maintain buoyancy

Answer 25

high oil content in liver changes don't have swim bladers

Question 26

how do deep sea fish maintain buoyancy

Answer 26

use lipids in a gas bladder or through body

Question 27

the _____ of aquatic vertebrates plays an important role in focus of light onto retina. what is diff between their ____ and a terrestrial vertebrate's?

Answer 27

lens fish have perfectly spherical one, terrestrial vertebrates have slightly compressed lens

Question 28

refractive index in fish

Answer 28

air = 1, water = 1.33, cornea = 1.37

Question 29

chemosensation

Answer 29

sensory system used to detect food, migration, etc.

Question 30

water displacement

Answer 30

sensory system have mechanoreceptors to sense touch, pressure, sound and motion lateral line system found in fish, larval amphibians and adult aquatic salamanders

Question 31

what are sensory systems in water

Answer 31

chemosensation, water displacement

Question 32

electricity and water

Answer 32

water conducts electricity some species can produce an electrical field: - to deter predators, courtship - territory defense

Question 33

electroreception

Answer 33

other vertebrates that can't produce electrical fields have this ex. sharks respond to small changes of electrical field via ampullae of lorenzini

Question 34

explain passive electroreception with shark example

Answer 34

sharks can locate live prey under sand preferentially attack electrical cue over olfactory cue when no electric, attacks olfactory without electric/olfactory cues, shark doesn't attack (fish may have created electrical field, insulating itself) shark attacks electrical cue from inanimate electrodes preferentially attack electrodes over dead bait