Scales Nails Claws Hoofs Antlers and Horns

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  1. Placoid scales

    1) organism

    2) structure

    3) function
    1) chondrichthyes (cartilaginous fish)

    2) really modified teeth that are covered with vitrodentine and have an inner core of pulp; give skin a rough feeling; develops in the dermis but projects through the epidermis to reach the surface; packed tightly together and grow with their tips facing backwards; similar to scales of bony fishes

    3) function: reduce drag in sharks
  2. Ganoid scales

    1) organism

    2) structure

    3) function
    1) bony fish

    2) rhomboid in shape with articulating peg and sockets in between; characterized by thick surface coat of enamel and a layer of ganoin, a hard inorganic salt substance, underneath; dermal bone forms the foundation and can be a double layer (vascular and lamellar bone) or a single layer of lamellar bone; shiny, overlapping, and interlocking; fit together like a jigsaw puzzle

    function: defense, leverage of muscles, and elasticity to body
  3. Teleost scales

    1) organism

    2) structure
    bony fish

    lacks enamel, dentin, and a vascular bone layer

    two kinds: cycloid and ctenoid
  4. cycloid scales
    a type of teleost scale

    Cycloid: composed of concentric rings (circuli) with a smooth surface and rounded margins
  5. Ctenoid scales
    a type of teleost scale

    Ctenoid: contains a fringe of projections along its posterior margin, a comblike processes on its outer part, and a serrate margin
  6. Cosmoid scale

    1) organism

    2( structure
    bony fish, though true ones are found in Crossopterygians

    structure: resides upon a double ayer of bone-- hard, thinner, outer vascular layer and an inner lamellar layer; consists of two basal layers of bone: a layer of dentine-like cosmine and an outer layer of vitrodentine

    probabyl evolved from fusion of placoid scales and scales become larger as new bone is added to the basal layers
  7. Nails

    1) organism
    2) structure
    3) function

    • plates of tightly compacted, cornified epithelium at the distal ends of the digits; the nail matrix (deep layer of epidermal tissue) forms new nail at nail base by pushing existing nail forward
    • The parts are the root (under the skin's surface), the body (visible external portion of the nail), and the free edge (the most distal end of the nail); consists of flattened unguis (dorsal scale-like plate)

    function: to protect end of digits, as well as for scraping and manipulating
  8. Claws

    1) organism

    2) structure

    3) function
    1) some amphibians; true claws are in reptiles, birds, and mammals

    2) structure: curved, pointed appendage at end of toe or finger; consists of dorsal scale-like plate covering a ventral plate; made of keratin

    3) used for catching and holding prey; digging, climbing, defensive mechanism, grooming
  9. Hoofs

    1) organism

    2) structure

    3) function
    1) ungulates

    2) keratinized plates on the tip of the digits; has a hoof wall (U shaped and open at heel; consists of keratinized stratum externa, the stratum medium , and the stratum internum); frog (wedge-shaed at bottom of hoof); sole (fills the ground surface space between the wall and triangular frog and consists of epidermis, dermis, and fatty digital cushion)

    function: support, propulsion, shock absorption, circulation, traction
  10. Horns

    1) organisms

    2) structure

    3) function
    1) umembers of the family Bovidae (ex: cattle, antelope, sheep, goats, bison, wildebeests)

    2) structure: retained year-round; unbranched and formed of a bony core and keratinized sheath; horns of proghorn family Antilocapridae are forked in adult males; hollow horrs in cattle, sheep, buffalo, goats, and other ruminents consist of an extension of the frontal bone

    function: defense from predators, tools in fighting other members of the species for territory or mating, feeding, courtship displays, and cooling
  11. Antlers

    1) organism

    2) structure

    3) fucntion
    1) members of the Cervidae family (typically males)

    2) solid bone with an overlying skin that shapes and provides vascular supply to the growing bone

    3) establish dominance (social hierarchy); act as hearing aids (moose); sexual selection
  12. Mammals are the only vertebrates with __.
    true horns or antlers
  13. The __ contributes to both true horns and antlers.
    skin, together with the underlying bone
  14. As these structures take shape (horns and antlers), what happens?
    the underlying bone rises up, carrying the overlying integument with it
  15. In horns, the associated integument...
    produces a tough, cornified sheath that fits over the bony core
  16. In antlers, ...
    the overlying skin (called velvet) apparently shapes and provides vascular supply to the growing bone. Eventually, the velvet falls away to unsheath the bare bone, the actual material of the finished antlers
Card Set:
Scales Nails Claws Hoofs Antlers and Horns
2015-09-26 05:43:36
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