Concept List: Bony Fish

Question 1

Describe the four general characteristics of Osteichthyes.

Answer 1

1. Bony endoskeleton
2. Paired fins
3. Gills covered by operculum
4. Swim bladder

Question 2

Describe and name the different anatomical features of a generalized ray-finned fish.

Answer 2

1. Bony rays supporting fins
2. Pectoral fins lifted on the sides, pelvic fins moved forward, anal fin

Question 3

What are the different scale types?

Answer 3

OLDER (thick, stiff):
Placoid: Tooth-like, blood supply, constant size, Osteichthyes.
Cosmoid: adapted placoid, rounded.
Ganoid: Rhomboid.

MODERN (softer, flexible)
Ctenoid: Looks like a comb
Cycloid: Smooth, rounded edge.

Question 4

Describe the role of scales. What do some fish use in place of scales?

Answer 4

Protect the outside of the body.
Prevents diffusion, allowing for more controlled osmoregulation.

Other fish may use mucus.

Question 5

Describe the changes seen in the Neopterygii

Answer 5

1. Increase in locomotory ability
2. Reduction in bony armor (size and thickness of scales)
3. Increased sucking ability of jaw
4. Increase gape and more circular opening of the mouth
5. Increased force of contraction when closing the mouth
6. Pharyngeal jaws

Question 6

How can you distinguish between ray-finned and lobe-finned fishes?

Answer 6

1. Fin placement
   - Lobe: “Limb” placement (like sharks)
   - Ray: Pectoral fins up and on the side, pelvic fins close to jaw
2. Internal fin structure
   - Lobe: Bones extend into fins
   - Ray: Bony projections into fins

Question 7

Name and describe the different body forms of fish.

Answer 7

Fusiform: torpedo-shaped
Compressiform: flattened laterally
Depressiform: Flattened top-bottom
Filiform: eel-like

Question 8

Define aspect ratio. What is its role in different forms of locomotion?

Answer 8

(Caudal fin height)^2/caudal fin area

High: thin and tall, low drag
Low: short and broad, high drag

Question 9

How can you distinguish between Chondrichthyes and Osteicthyes?

Answer 9

Skeletal composition.
Absence/presence of a swim bladder.

Question 10

What are the different arguments for either Chondrichthyes or bony fish being described as
the most successful vertebrate group?

Answer 10

Chondrichthyes: They are mid- to top-level predators anywhere they exist.

Osteichthyes: Found in every body of water on earth.

Question 11

What are the different environments a bony fish can occupy?

Answer 11

Anywhere there is water.
Fresh, salt, hot, cold, lakes on mountains, caves, land (mudskippers) etc.