Fish features and form

Question 1

Name the fins found on cartilaginous fish

Answer 1

• Unpaired first and second dorsal fins (medially)
• 2 sets of paired lateral fins: pectoral and pelvic
• Caudal fin

Question 2

What is the intermittent organ for internal fertilisation in male cartilaginous fish?

Answer 2

Pelvic fins with claspers

Question 3

How many gill slits and gill arches are present in cartilaginous fish?

Answer 3

5 external gill slits with 4 internal gill arches (on either side)

Question 4

What is the function of the lateral line organ?

Answer 4

Mechanoreceptors - detecting water pressure changes on body surface

Question 5

Describe how the lateral line system works in cartilaginous fish

Answer 5

• Expands greatly on the head
• Consists of pores that open into internal channels that contain neuromast cells
• The sensory hair within these detect movement and water pressure changes

Question 6

What allows a shark to detect weak muscle contraction of other organisms to locate them?

Answer 6

Ampullae of Lorenzini

Question 7

Water has a much higher …, … and … than air

Answer 7

Density, Specific heat capacity and Viscosity

Question 8

How do fish need to be adapted to water as a respiratory medium?

Answer 8

• Energy cost of ventilation is high

- Much higher ventilation rates are needed to meet oxygen demand

Question 9

Describe the anatomy of a fish gill and how this makes it adapted to maximise oxygen extraction from water

Answer 9

• Unidirectional flow
• 4 gill arches on each side with 2 rows of filaments
• Filaments contain hundreds of lamellae
• Large surface area
• Pressure pump
• Counter current flow of water and blood
• Thin lamellae provide a short diffusion distance

Question 10

How is drag (caused by high viscosity) reduced?

Answer 10

• Rounded body shape
• Maximal diameter composing of 1/4 of length
• Reduced scale size
• Mucus covering

Question 11

Which 4 force act on a fish?

Answer 11

• Drag
• Thrust
• Gravity
• Lift and buoyancy

Question 12

In what form is nitrogenous waste excreted in fish?

Answer 12

Ammonia

Question 13

Describe osmoregulation in salt water fish

Answer 13

• osmotic water loss through gills and other parts of the body surface
• gains of water and salt ions from food and drinking
• excretion of salt ions from gills
• excretion of salt ions and small amounts of water from kidneys

Question 14

Describe osmoregulation in freshwater fish

Answer 14

• osmotic water gain through gills and other parts of the body surface
• uptake through the mouth of water and some ions in food
• uptake of salt ions through gills
• excretion of large amounts of water in dilute urine from kidneys

Question 15

How are fishes adapted to living in water which has a high specific heat capacity?

Answer 15

Ectotherms - body temperature determined by environmental temperature

Question 16

How is circulation different in fish to mammals?

Answer 16

Single loop circulation

• Low pressure circulatory system
• No blood ‘pooling’ in lower appendages

Question 17

Which systems of a fish can be considered together and why?

Answer 17

Urinary and reproductive (close association)

• Both develop embryonically from mesoderm
• Walls of trunk, upper rim of coelom are closely together
• Use of common ducts

Question 18

Urine is released from the kidneys in fish by which duct?

Answer 18

Archinephric duct