Gas exchange in aquatic animals

Question 1

How do sessile molluscs meet their oxygen needs?

Answer 1

Gills, unidirectional counter current, water moved with cilia

Question 2

How do clams meet their oxygen needs?

Answer 2

Flat sheet-like gills with filaments to increase surface area. Unidirectional counter current

Question 3

How do cephalopods meet their oxygen needs?

Answer 3

Muscle contractions of the mantle cavity will move water across their gills. Unidirectional countercurrent

Question 4

How do land snails meet their oxygen needs?

Answer 4

Highly vascularized mantle cavity. Unidirectional countercurrent

Question 5

How do crustaceans meet their oxygen needs?

Answer 5

Use gill bailers to drive water across the gills and out the mouth. Unidirectional counter current

Question 6

How do sea stars meet their oxygen needs?

Answer 6

Uses respiratory papulae and tube feet. Move water from the mouth and through the papulae. Unidirectional counter current

Question 7

How do sea cucumbers meet their respiratory needs?

Answer 7

Respiratory tree. Water passes through the digestive tract and the respiratory tree takes the oxygen as it passes by. Unidirectional countercurrent

Question 8

What ventilation system do jawless fish use?

Answer 8

Tidal (unidirectional tidal)

Question 9

How do hagfish meet their respiratory needs?

Answer 9

The velum pumps water from the mouth, through the gill sacs, and out the gill opening. Unidirectional counter current

Question 10

How do lamprey meet their respiratory needs when they aren’t feeding?

Answer 10

Similar to the hagfish, where velum pumps water from the mouth, across the gills, and through the gill opening out.

Question 11

How do lamprey meet their respiratory needs when they are feeding?

Answer 11

Unidirectional tidal ventilation through the outer openings. They get a lot from the host

Question 12

What ventilation system do elasmobranchs use?

Answer 12

Buccal pump

Question 13

How does the buccal pump work?

Answer 13

The fish sucks in water through the mouth and spiracles, closes the mouth and pressure increases in the buccal cavity, then the cavity contracts and forces the water through thegill slits

Question 14

What ventilation system do teleost fish use?

Answer 14

Buccal opercular pump

Question 15

What is the gill structure in teleost fish?

Answer 15

Gills are arranged into gill arches. The arches are V shaped and have 2 layers of gill filaments, and the gill filaments have two rows of lamellae

Question 16

What did Hughes and Shelton do?

Answer 16

Did a bunch of pressure measurements in a trout to determine how the buccal opercular pump works

Question 17

What were the 4 things Hughes and Shelton measured?

Answer 17

1. Opening and closing of the mouth and buccal valve
2. Opening and closing of the operculum
3. Pressure in the buccal cavity
4. Pressure in the opercular cavity

Question 18

What happens in phase 1 of the buccal opercular pump?

Answer 18

The mouth opens, buccal cavity expands, buccal valve opens, operculum expands, opercular valve closed. Negative pressure in the opercular cavity and positive pressure in the buccal cavity

Question 19

What happens in phase 2 of the buccal opercular pump?

Answer 19

Mouth closes, buccal valve closes, buccal cavity expands, opercular cavity expands, opercular valves closed. Positive pressure in buccal cavity and negative pressure in the opercular cavity

Question 20

What happens in phase 3 of the buccal opercular pump?

Answer 20

Mouth closed, buccal valve closed, buccal cavity contracts, opercular cavity contracts, opercular valves open. Positive pressure in the buccal cavity.

Question 21

What happens in phase 4 of the buccal opercular pump?

Answer 21

Mouth opens, buccal valve opens, operculum contracts completely, opercular valves close. Negative pressure in the buccal cavity

Question 22

What were the 3 things that Hughes and Shelton concluded from their experiment?

Answer 22

1. Positive pressure in the buccal cavity in phases 1, 2, 3
2. Negative pressure in the opercular cavity in phases 1,2
3. Highly coordinated and takes about 0.5 seconds to complete a full cycle

Question 23

What fish use ram ventilation?

Answer 23

Some teleost fish like tuna and mackerel that swim rapidly for long periods of time

Question 24

Why do tuna use ram ventilation?

Answer 24

They are so active that the buccal opercular pump isn’t enough

Question 25

How does ram ventilation work?

Answer 25

The fish swim with their mouth open and constantly force water through the gills