Just scales

  1. Explain the structure of epidermal scales.
    horny, tough extensions of the stratum corneum

    periodically molted or shed gradually along with the rest of the stratum corneum
  2. Organisms that have epidermal scales
    well developed in reptiles; also common on exposed skin in birds (confined to lower legs, feet, base of bill) and mammals

    absent in fish

    clawlike epidermal scales are present in certain amphibians; horns of hte horned lizard are specialized epidermal scales

    these scales cover the bony scales of the carapace and plastron of turtle shells
  3. Composition of cosmoid scales

    scale shapes
    enamel,. dentine (cosmine) vaxular and lamellar bone), thinner, and have dentine of cosmoid type

    cycloid or rhomboid
  4. Ganoid scales

    Thick, rhomboid, evolved from cosmoid scales.

    Ganoin,vascular bone and lamellar bone
  5. Teleost scales
    Derived from ganoid scale of lepidosteoid type.

    • Scales thin, imbricated, and cycloid or ctenoid
  6. Placoid scales (dermal denticles)
    Evolved from cosmoid scales?

    Lack the bony basal layer of scales.

    • Pulp cavity surrounded by dentine--this capped with enamel.
Card Set
Just scales