Fish dissection

Question 1

What is considered the head of a fish?

Answer 1

the anterior end, posterior to the last gill slit

Question 2

What are the major features of a fish head?

Answer 2

snout
eyes
mouth
tongue
operculum (gill cover)
branchiostegal rays
isthmus
gill membrane
gill cavity

Question 3

What features does the snout have?

Answer 3

external nares (nostrils)

Question 4

What kind of organs are the external nares (nostrils) of a fish?

Answer 4

olfactory only, no respiratory function

Question 5

T or F: external nares of fish are both olfactory and respiratory organs

Answer 5

false. Only olfactory, they are blind-ended sacs and not connected to the oral cavity

Question 6

T or F: fish sleep with their eyes open, why / why not?

Answer 6

true because fish don’t have movable eyelids

Question 7

How does the vision of fish that live in shallow water compare to fish in deeper water?

Answer 7

shallow water: tend to have colour vision

deeper water: have reflective crystals to enhance vision in poor light conditions (reflective green)

Question 8

What is the mouth margin of a fish called?

Answer 8

gape

Question 9

Which two bones may contribute to the gape in a bony fish?

Answer 9

maxilla or premaxilla

Question 10

Describe fish tongues

Answer 10

either cartilaginous or bony

immobile

not involved in food consumption

might have teeth

Question 11

T or F: fish tongues are muscular

Answer 11

false - they are either cartilaginous or bony

Question 12

What is unique about bony fish tongues?

Answer 12

they are cartilaginous or bony
some have teeth
not involved in eating

Question 13

What is the function of the operculum?

Answer 13

it covers and protects the gill openings and controls water flow over gills

Question 14

Which fish groups have operculums? which don’t?

Answer 14

operculum present:
bony fish
ratfish (cartilaginous)

operculum absent:
cartilaginous fish (shark, rays)
marine eels

Question 15

What are branchiostegal rays?

Answer 15

fanned, parallel bony struts that connect skin membranes under and beside the mandible/lower jaw

Question 16

What are branchiostegal rays used for?

Answer 16

allow for drawing in water into mouth

Question 17

What is the isthmus?

Answer 17

the skin that runs underneath (ventral) and connects the sides of the lower jaw

Question 18

What are the gill membranes?

Answer 18

membranes that cover the gill cavity and are supported by the branchiostegal rays

Question 19

What is a holobranch?

Answer 19

another name for a gill

Question 20

How many holobranchs do most bony fish have?

Answer 20

4

Question 21

What is the gill cavity?

Answer 21

underneath the operculum where the gill arches (holobranchs) are located

Question 22

What form the respiratory surface?

Answer 22

the gill filaments

Question 23

What is the name of the body compartment behind the head?

Answer 23

the trunk

Question 24

Describe the trunk

Answer 24

posterior to the last gill slit to the base of the tail

Question 25

What are the two major components of the trunk?

Answer 25

Paired fins unpaired fins

Question 26

What are the most obvious features of the trunk?

Answer 26

fins

Question 27

What are the two paired fins?

Answer 27

pectoral fins - anterior pelvic fins - posterior

Question 28

What are the pectoral fins attached to?

Answer 28

the pectoral girdle

Question 29

In more advanced bony fishes, what are the pelvic fins attached to?

Answer 29

the pelvic girdle, but it in some it has migrated up and fused to the pectoral girdle

Question 30

What are the 5 unpaired fins?

Answer 30

dorsal finlets anal fin caudal fin adipose fin

Question 31

In what ways can the dorsal fin(s) be present?

Answer 31

always along the dorsal midline can be single, paired, or in threes can be a single continuous fin

Question 32

In some fish, what are the dorsal fins used for?

Answer 32

propulsion

Question 33

In more advanced bony fish, what else can be present with the dorsal fins?

Answer 33

spines - rigid, inflexible rays - soft, flexible

Question 34

What are finlets?

Answer 34

small numerous flag-like projections

Question 35

Where are finlets located?

Answer 35

between dorsal and caudal fins or posterior to the anal fin

Question 36

Which kind of fish would have finlets? why?

Answer 36

fast-swimming fish like tuna and mackerel because they likely function to reduce drag

Question 37

Where is the anal fin located?

Answer 37

midventrally and posterior to the anus

Question 38

How many anal fins can be present?

Answer 38

one or two

Question 39

What is the function of the anal fins?

Answer 39

prevent rolling - acts as a vertical stabilizer

Question 40

What type of fish will usually lack anal fins?

Answer 40

bottom-dwellers

Question 41

How does the shape/size of the caudal fin vary?

Answer 41

it depends on the fish's swimming style

Question 42

describe the adipose fin? where is it located?

Answer 42

small soft located posterior to dorsal fin

Question 43

What type of fish have adipose fins?

Answer 43

salmoniforms

Question 44

What is the lateral line system?

Answer 44

a sensory system that runs laterally from the head to the tail

Question 45

What is the lateral line system composed of?

Answer 45

jelly-filled canals with specialized sense organs (neuromasts)

Question 46

What is the function of the lateral line system?

Answer 46

to feel pressure changes caused by vibrations from moving prey

Question 48

What are the 4 types of fish scales?

Answer 48

placoid ganoid cycloid ctenoid

Question 49

What kind of scales do fish without spiny dorsal fins have?

Answer 49

cycloid scales

Question 50

what kind of scales do fish with spiny rays in dorsal fins have?

Answer 50

ctenoid

Question 51

Describe placoid scales - what type of fish have these?

Answer 51

aka dermal denticles tiny, unlayered tooth-like scales characteristic Chondrichthyes

Question 52

Describe ganoid scales - what type of fish have these?

Answer 52

heavy plate-like form a body armour ancestral fish like bichirs, gar, stugeons

Question 53

Describe cycloid scales - what type of fish have these?

Answer 53

thin round smooth flat overlapping soft-rayed fish - salmon, trout

Question 54

Describe ctenoid scales - what type of fish have these?

Answer 54

tiny, comb-like projections on exposed end rough mostly spiny-rayed fish - ex. perch

Question 55

Describe the circulation circuit of fish hearts

Answer 55

single circuit - blood passes through the heart once per circuit

Question 56

how many times does blood pass through the heart per circuit ?

Answer 56

once

Question 57

What is the swim bladder?

Answer 57

a thin-walled sac in the dorsal body cavity to adjust buoyancy

Question 58

T or F: jawless fish (lamprey and hagfish) lack a true stomach

Answer 58

true