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Flashcards in Extreme environments Deck (39):
1

How much of earth's surface is covered in water?

2/3rds

2

How much of water is fresh?

1%

3

Why does the composition of freshwater vary so much?

Because of variation in geographical location.

4

What problems do living in freshwater, brackish or marine water pose?

Osmoregulatory problems

5

What is osmoregulation?

The maintenance of solute and water balance.

6

What is osmosis?

The passage of water through a semi permeable membrane from a weaker solution to a stronger solution.

7

What does the movement of water molecules depend on?

Depends on the number of particles and osmotic pressure.

8

What is osmotic pressure measured in?

osmoles - milliosmoles

9

What is the osmotic pressure for sea water?

1000 mOsm

10

What is the osmotic pressure for a marine invertebrate?

Same osmotic pressure as sea water but ionic composition may be different.

11

What is an osmoconformer?

If the external medium changes then the vertebrate changes its fluids to match the external medium.

12

What is an osmoregulator?

A vertebrate that maintains or regulates osmotic concentration despite external changes.

13

When would a vertebrate use hyper osmotic regulation and why?

If a freshwater or marine invert was living in an estuary which would cause a loss of ions due to inflow of water.

14

What is carried out during hyper osmotic regulation?

Active ion transport.

15

What do inverts use for active ion transport?

Organs

16

What do crustaceans and aquatic animals use for active ion transport?

Gills

17

What are the problems with hyper osmotic regulation?

Body fluids are more dilute than environment and there is an accumulation of ions and loss of water.

18

In Artemia (brine shrimp) how do they deal with living in salt lakes?

Artemia swallow vast quantities of water but actively secrete salts either from the neck gland in larvae or from the gills in an adult.

19

What is the osmotic concentration of a marine living hagfish?

Similar to sea water at 1000 mOms

20

What do iso osmotic hagfish regulate?

Sodium

21

What is the osmotic concentration of a fresh/marine living lamprey?

1/3 of the sea so 333 mOms.

22

What is the osmotic balance of elasmobranchs (sharks/rays)?

Similar to sea water (1000 mOms) but salt content remains at about 1/3 of sea water.

23

How do elasmobranchs eliminate sodium?

Through the kidneys, gills and rectal glands.

24

What is the osmotic concentration of freshwater and marine Teleosts?

1/3 of sea water. (333 mOms)

25

What are marine teleosts in danger of?

Drinking lots of water.
Increased salt concentration.
Chloride cells eliminate excess.
Mg and Sulphate excreted by kidneys.

26

What are freshwater teleosts in danger of?

Vast amounts of dilute urine.

27

How do sea mammals excrete salt?

Through concentrated urine.

28

Describe an ideal gas exchange site.

Large surface area.
Thin epithelial layers.
In contact with medium.

29

What is the definition of diffusion?

Substance moves from a higher to lower concentration.

30

What is cutaneous gas exchange?

Gas exchange that occurs over the general body surface through skin.

31

What is a gill?

Respiratory surface protruding, turned outwards forming an evagination.

32

Describe a tuft gill and what animal can it be found on.

A raised thin area of skin or simple tuft. Can be found on the papulae of starfish.

33

Describe a filament gill

Feather like structures supported by thin external cuticle with elaborate blood flow.

34

Describe a lamellate gill

Flat plates extend from a central strut or gill arch with specific orientation to water flow. Maybe protected by a gill cover.

35

What is an operculum?

The protective cover over the gill cavity.

36

How do fish get oxygen?

Oxygen rich water flows between lamellae in gills and blood flows within them in the opposite direction. (counter-current flow)

37

When would there be uni-directional flow over gill surface.

When water is pumped over gill by the mouth and opercular pump.

38

Why would a fish need to keep swimming in order to keep the uni-directional flow?

If there is no opercular pump.

39

What is a lung?

Respiratory surface completely internalised and forms from an invagination.