external anatomy

Question 1

anterior (placement)

Answer 1

towards the top or head end of the body

Question 2

posterior (placement)

Answer 2

towards the back or tail end of the body

Question 3

cranial (placement)

Answer 3

head region

Question 4

caudal (placement)

Answer 4

tail region

Question 5

dorsal (placement)

Answer 5

towards the top (back / spinal) area of the body

Question 6

ventral (placement)

Answer 6

towards the underside of the body

Question 7

tall, narrow body shape

Answer 7

adapted to live in slow moving water

Question 8

torpedo-shaped body

Answer 8

adapted to live in fast moving water

Question 9

superior mouth

Answer 9

• top swimmers
• straight dorsal surface
• upturned, scoop like mouth

Question 10

terminal mouth

Answer 10

• mid water swimmers
• mouths at the tip of the snout

Question 11

inferior mouth

Answer 11

• bottom-dwellers
• flattened ventral surface
• downturned / underslung mouth

Question 12

larger eyes

Answer 12

generally seen in deep-water fish

Question 13

smaller eyes

Answer 13

generally seen in shallow-water fish

Question 14

dilating pupils

Answer 14

• seen in some species (e.e. shark and eels)
• not seen in bony fish usually

Question 15

nostrils

Answer 15

• not used for breathing
• water will pass through
• detects chemical traces at the base of the nostril
• essential in low visibility
• may have one pair, two pairs or a single nostril

Question 16

skin

Answer 16

• defence against pathogens through mucous layer that entraps and immobilises pathogens

Question 17

scales

Answer 17

• bony material
• placoid scales, ganoid scales, ctenoid scales, cycloid scales
• scutes (on catfish)

Question 18

placoid scales

Answer 18

• found in rays and sharks
• resemble teeth-like projections
• do not increase in size, but in numbers as the fish grows

Question 19

ganoid scales

Answer 19

• mosaic in arrangement with overlaps
• seen on sturgeons and gar fish

Question 20

ctenoid scales

Answer 20

• have a spiny comb or teeth-like extensions to the outer edge
• perch fish have ctenoid scales

Question 21

cycloid scales

Answer 21

• are round or oval shaped
• grow with the fish → creates growth rings which determines a fish’s age

Question 22

scutes

Answer 22

• in place of scales on armoured catfish
• their bodies are covered with two or three overlapping bony plates

Question 23

fin functions

Answer 23

• stability
• propulsion
• steering
• balance

Question 24

dorsal fin

Answer 24

• located along the back of the fish (between tail fin and head)
• provides lateral stability to allow swimming in a straight line and prevents it from rolling over

Question 25

caudal fin

Answer 25

• aka tail fin
• located at the rear of the fish
• responsible for propulsion + fast swimming patterns
• can be used to slow forward movements and for turning

Question 26

anal fin

Answer 26

• located on the underside of the body between the pelvic and caudal fin
• helps with stability + steering
• prevents fish from rolling over

Question 27

pectoral fins

Answer 27

• paired and located near the bottom of the fish, directly beneath the gill openings
• used in navigation and stability
• provide the upward lift that helps fish maintain depth + enables the flight go flying fish
• can be adapted for “walking” above or below water on some fish
• can have defensive spines

Question 28

pelvic fins

Answer 28

• located in front of the anal fin, on the abdomen of the fish (underside)
• used for braking, stabilising + changing direction

Question 29

adipose fin

Answer 29

some fish (e.e. tetras) have an additional fin located between the dorsal and caudal fins

Question 30

lateral line

Answer 30

• helps detect vibrations and currents while underwater
• senses water movement and pressure
• pressure around objects are distorted which is detected by the lateral line; allowing a fish to change direction
• enables fish to escape predators, catch prey and take part in a shoal