Skeleton of Fishes

Question 1

(VERY) Briefly describe the structure and function of the skeleton

Answer 1

Structure: consists of bone, cartilage, ligaments, tendons
Function: support weight, protection, anchors muscle, stores minerals

Question 2

What are the three main components of the skeleton?

Answer 2

• skull
• axial skeleton (vertebral column, ribs)
• appendicular skeleton (girdles + fins/limbs)

Question 3

What are the three components of the skull?

Answer 3

• chondrocranium
• splanchnocranium
• dermatocranium

Question 4

Which skull component is not present in the agnathan skull?

Answer 4

Dermatocranium (agnathans have no jaws)

Question 5

How does the Teleost skull vary from other fish skulls?

Answer 5

• has all three parts but small chondrocranium
• more bones, less connections
• more maneuverability in jaws
• diversity in bone number and size

Question 6

How does the Teleost skull differ from that of gnathostomes?

Answer 6

Teleosts: narrow mouth, hinge more forward, upper and lower jaws move separate from braincase ->suction feeding
Gnathostomes: wide mouth, hinge far back, upper jaw fused with braincase

Question 7

Suction feeding in Teleosts is driven by change in ___ of the chamber, using premaxilla, _____, and ______.

Answer 7

1. volume
2. maxilla
3. hyoid apparatus

Question 8

What does it mean to have an autostylic jaw?

Answer 8

• upper jaw is braced against braincase
• hyomandibula does not play a role in bracing jaws
• seen in placoderms and lungfishes

Question 9

What does it mean to have an amphistylic jaw?

Answer 9

• hyomandibula acts as strut, helps brace jaw with braincase

- seen in some sharks and bony fishes

Question 10

What does it mean to have a hyostylic jaw?

Answer 10

• mandibular arch is supported mostly by hyomandibula

- seen in most sharks and bony fishes

Question 11

What are the main components of the axial skeleton?

Answer 11

• centrum, encapsulates notochord
• neural arch, protects spinal cord
• hemal arch, protects blood vessels
• processes

Question 12

How does the teleost differ from early fishes when it comes to the axial skeleton and the notochord?

Answer 12

• notochord greatly reduced

- ligaments and ribs prevent dislocation

Question 13

T or F: the notochord remains throughout life in some fish, but is replaced by centra in others

Answer 13

True

Question 14

What are the different primary functions of the different types of fins?

Answer 14

Paired fins: stability, fine control
Median fins: prevents body from rolling
Caudal fin: propels fish forward

Question 15

What structures are present in fins?

Answer 15

• pterygiophores and flexible rays, strengthens membranes
• rigid spines
• keratinized rods (elasmobranchs)
• bone/cartilage (bony fishes)
• keratinized tips (bony fishes)

Question 16

How does the pectoral girdle vary between sharks and Teleosts?

Answer 16

• in sharks two halves are fused in midline but not joined to skull
• in teleosts the girdle is joined to skull by cleithrum bones for strength