Lecture 3 skin and skeleton

Question 1

Scale growth

Answer 1

Scales originate in the dermis and grow into the epidermis, if the scales are exposed it means the epidermis is destroyed

Question 2

epidermis (4)

Answer 2

top ~10-30 cell layers

can have mucus, venom, pigment, photophore cells

may secrete cuticles and tubercles

covers scales and plates

Question 3

Dermis (3)

Answer 3

Connective tissues with few cells

can contain pigment, blood vessels, nerves and dermal skeleton

2 sets of opposing collagin spirals to allow wrinkle free bending

Question 4

collagen Spirals

Answer 4

Collagen spirals (one clockwise one counter clockwise) allow for the fish to bend without wrinkles = less drag in the water

Question 5

dermal skeleton types (scales) (3)

Answer 5

Placoid “tooth-like” - sharks; bone cells in base with dentine covering

ganoid “plate-like” - sturgeons; bone in basal plate, ganoin over dentine

teleost “scale-like” - mineralized layer over collagen, posterior is either smooth (cycloid ) or spiny (ctenoid)

Question 6

teleost vertebrae Label and function (7)

Answer 6

A. Dorsal neural spine :canal for nerve cord
B. neural arch
C. Centrum (centra plural): canal for the notocord
D. pleural ribs : encase viscera
E. intermuscular bone : only in some species
F. Hemal canal : canal for dorsal aorta
G. zygopophyses: limit movement, interlocking in faster fish like tuna

Question 7

Label pectoral and pelvic girdles

Answer 7

A. Posttemporal
B. supracleithrum
C. Cleithrum
D. scapula
E. Fin Rays
F. postcleithra
G. radials
H. coracoid
I. Fin spine
J. soft rays
K. Pelvic Bone
L. mesocoracoid

Question 8

Dorsal Fin Rays (3 types)

Answer 8

Elasmobranches (sharks and rays) : basal cartilage separated into proximal, middle, and distal segments

teleost (soft): 2 joined bones per ray, may be branched (fan shaped) at ends

Teleost (spiny) : hard, undivided and unbranched

Question 9

Elasmobranch Skull (2)

Answer 9

chondroneeurocranium: a cartilaginous box (sometimes calcified) with openings for blood vessels and nerves called foramina and fenestrae

mandibular arch indirectly attached to hyoid arch

Question 10

Low teleost skull (5)

Answer 10

-retains much cartilage

-ossification replacing cartilage is referred to as perichondral & endochondral bone

-upper jaw: premaxillary and maxillary main tooth bearing bones

-lower jaw: dentary is the main tooth bearing bone

-4 dermal bones form operculum to protect gills & part of branchial pump

Question 11

high teleost skull (3)

Answer 11

-general trend toward greater ossification

-more bones around the orbit

• less lower jaw bones than nonteleost fish