17. Fish

Question 0

Function of pharyngeal slits (pouches)?

Answer 0

• Filter feeding

- Respiration in vertebrates

Question 1

…

Answer 1

…

Question 2

Gills are used for…

Answer 2

Exchange of O2 and CO2 (respiratory surface)

Question 3

Pharyngeal slits can become…

Answer 3

Gill slits

Question 4

What are the bars between the slits?

Answer 4

Gill arches (bone or cartilage)

Question 5

What is on the gill arches?

Answer 5

Gill filaments

Question 6

How many pairs of gill arches in bony fishes?

Answer 6

4 (each arch has pairs of gill filaments) _ gill cover (operculum) to protect

Question 7

Gill filament structure = ……., ……, ……. area

Answer 7

Thin, vascularized, high surface

Question 8

Blood flow and water in gill filament?

Answer 8

• Blood vessel flow through gill arches
• Capillary beds in gill filaments (gas exchange - filament only one cell thick)
• Water & Blood flow in opposing directions (counter-current exchange system)

Question 9

Explain countercurrent exchange.

Answer 9

• Blood flows in opposite direction to water flow
• Ensures that concentration gradients are maintained
• Achieves maximum exchange of gases

(the more oxygenated the water, the more oxygenated the blood)

Question 10

Describe the fish circulatory system

Answer 10

• Closed (arteries, arterioles, capillaries, venules, veins) (not quite like ours, we have pulmonary and systemic (lungs vs body), but not the fish)

Question 11

Describe the fish heart

Answer 11

2 chambers & folded (blood comes in through sinus venosus, the one-way valves inside, atrium, ventricle, bulbous arteriosus) - found ventrally

Question 12

Characteristics of vertebrates?

Answer 12

• Axial skeleton (cranium, vertebral column, ribs)
• Apendicular skeleton (pectoral girdle, pelvic girdle)
• Closed circulatory system (with ventral heart)
• Organs suspended in coelom

Question 13

Fish make up what % of vertebrate diversity?

Answer 13

50%

Question 14

What are gnathostomes?

Answer 14

Jaw fishes

Question 15

Vertebrates but not gnathostomes - 2 groups?

Answer 15

Lampreys & Hagfish

• No jaw, paired fins, swim bladder, scales
• Cartilaginous skeleton, gill slits, notochord

Question 16

Hagfish - feeding?

Answer 16

Scavengers

Tie a knot to eat - use it as a jaw to rip off the food

Question 17

Hagfish regulation?

Answer 17

Osmotic concentration same as seawater - no regulation of ions

Question 18

What hagfish characteristics make their designation as vertebrates debatable?

Answer 18

No vertebral column, partially closed circulatory system (accessory hearts), partial cranium.

Question 19

Characteristics of lamprey?

Answer 19

• Very common
• No jaw, but oral disk with teeth
• Very distinct larval form (ammocyete)
• Adults are often parasitic on other fishes

Question 20

Jaws are formed by…

Answer 20

Fusion of gill arches

Question 21

Evolution of jaws?

Answer 21

• Not present in early fishes and now agnathans

- Teeth evolved from scales in the mouth

Question 22

Advantage of jaw?

Answer 22

Improves ability to feed and diversify

Question 23

Paired fins?

Answer 23

• On Pectoral and pelvic limb girdles
• Enables more active swimming
• Used for steering, stabilizing, lift

Question 24

What are Chnodrichthyes?

Answer 24

Cartilaginous fishes: Sharks, skates, rays

Question 25

Anatomy of Chondrichthyes?

Answer 25

- Jaws - Paired fins - 5-7 fins pair .....catch up

Question 26

Smallest and largest shark?

Answer 26

``` Dwarf lantern shark (16 cm) Whale shark (18 m) - biggest fish in the world ```

Question 27

Osteichthyes?

Answer 27

Bony fishes - largest vertebrate group

Question 28

Swim bladder?

Answer 28

Flotation device Enables neutral buoyancy Gas regulated by gland in bladder or by swallowing/burping air

Question 29

Two groups of bony fish?

Answer 29

1. Ray-finned fishes | 2. Lobe-finned fishes