Chapter 6: integument

Question 0

Epidermis

Answer 0

(Newer) 
Surface
Cellular
Ectoderm
Evolutionary variety

Question 1

Functions

Answer 1

Protection from... Abrasion, mechanical injury, infection, uv radiation
Regulate water content
Heat transfer
Color (camouflage, communication)
Respiratory gas exchange
Sense reception

Question 2

Dermis

Answer 2

(Old structure)
Deep
Fibers & some cells (matrix)
Mesoderm
Uniform (some bone variety)

Question 3

Evolutionary themes

Answer 3

1) development of dermal bone -> loss of bone later
2) degree of specialization of epidermis -> increase of bone
* keratinized stratum corneum
3) degree of development of skin glands -> increase later on

Question 4

Ostracoderm integument

Answer 4

Dermal shell of bony plates

• dentin layer on outside (hard material)
• spongy bone in middle (lattice like)
• lamellar [sheet] bone (dense layers)

Question 5

Other Agnatha integument

Answer 5

Secondary loss of dermal bone = no scales

Question 6

Placoderm integument

Answer 6

Smaller, thicker plates = armor
-denticles (enamel spines)
   >little tooth (Latin)
-dentin
-spongy
-lamellar

Question 7

Cartilaginous fish integument

Answer 7

• dermal bone absent (Dentin, spongy, lamellar)
• tiny placoid scale (denticle only)
• tough, sand-papery skin

Question 8

Bony fish integument

Answer 8

-denticle absent
-retain deeper layers; especially lamellar
-cycloid scale (dermal) >parrot fish
-ctenoid [comb] scale (dermal) >sunfish
-ganoid scale (dermal + thick coat enamel)
>gar fish and bowfin fish (amia)

Question 9

Dermal elements of bony fish

Answer 9

-scales
-dermatocranium
-pectoral girdle (fused up into skull)
Ventral: Clavicle
Cleithrum
Supracleithrum
Dorsal: Post temporal
-operculum (gill cover)

Question 10

Dermal elements of other vertebrates

Answer 10

• clavicle
• osteroderms (bony plates) in crocodiles
• carapace + plastron in turtles: scutes = epidermal
• armadillo shell
• chromatophores (contain pigment) in dermis of fish, amphibians, reptiles

Question 11

Epidermal Seal

Answer 11

1) cuticle= continuous, nonliving material secreted by epidermis *larvae
2) mucoid coat= glycoprotein; only in aquatic vertebrates
3) keratinized stratum corneum
>amphibians-amniotes (more keratin)
-good seal in dry air
-keratin protein in surface cell layers
-mainly in amniotes = terrestrial/dry

Question 12

Epidermal examples

Answer 12

1. Epidermal scales & modified scales
   >reptiles
   >birds
  -unmodified scales on legs and feet
  -modified scales + feathers (homology)
   >mammals
  -unmodified scales on tail (beaver, rat)
2. Hair is a new structure, not just modified scales (invagination)
3. Claws, nails, hooves 
 -reptiles developed first, modified later
4. Horn sheath -elaborate
5. Antler velvet 
  -beneath is dermal bone
6. Rattlesnake rattles
7. Bird beaks/ turtle beaks 
8. Whale baleen (strainers to collect krill)
9. Ishial callosities (monkeys)
10. Tori 
11. Skin glands
 >epidermal, then sink down into dermis (invagination--like hair follicles)
  -mucous glands
  -poison glands
  -sebaceous glands
  -"sweat" glands
  -mammary glands

Question 13

Dermal/Epidermal interactions

Answer 13

• teeth
• placoid scales
• feathers