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Skeletal System, Skin, & Scales Chapter 3 - PowerPoint PPT Presentation


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Skeletal System, Skin, & Scales Chapter 3. Fish Skulls. Neurocranium Chondocranium Dermatocranium Splanchiocranium Gills Jaws. Ethmoid Region. Medial Ethmoid Lateral Ethmoids Vomer. Orbital Region. Frontals Parasphenoid Pterosphenoid Orbitosphenoid Basisphenoid Infraorbitals

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fish skulls
Fish Skulls
  • Neurocranium
    • Chondocranium
    • Dermatocranium
  • Splanchiocranium
    • Gills
    • Jaws
ethmoid region
Ethmoid Region
  • Medial Ethmoid
  • Lateral Ethmoids
  • Vomer
orbital region
Orbital Region
  • Frontals
  • Parasphenoid
  • Pterosphenoid
  • Orbitosphenoid
  • Basisphenoid
  • Infraorbitals
  • Preorbitals (lacrymal)
  • Postorbitals
  • Suborbitals
otic region
Otic Region
  • Parietals
  • Sphenotic
  • Pterotic
  • Prootic
  • Epiotic
otic region7
Otic Region
  • Parietals
  • Sphenotic
  • Pterotic
  • Prootic
  • Epiotic
basichranial region
Basichranial Region
  • Supraoccipital
  • Exocipitals
  • Basiocipital
  • Parasphenoid
jaw structure
Jaw Structure
  • Premaxilla
  • Maxilla
  • Supramaxilla
  • Palatine
  • Dentary
gill coverings
Gill Coverings
  • Preopercle
  • Opercle
  • Subopercle
  • Interopercle
  • Branchiostegals
slide17

Soft Finned Rays

Spines vs. Rays

Rays

Soft, unpointed

Segmented

Branched

Bilateral (lt. and rt. halves)

Spines

Hard, pointed tissue

Unsgemented

Unbranched

Solid

caudal fins
Caudal Fins
  • Caudal fins are highly variable in shape but essentially serve the same function; that being forward motion, although some do it better than others and some provide additional benefits.
slide23

Leptocercal—dorsal and anal rays joined with caudal

  • around posterior of fish (lungfishes, coelocanth).
slide24

Heterocercal—unequal lobed, vertebral column extends

  • into the upper portion (sharks, sturgons, gar)
slide27

Gephyrocercal—”bridge tail”

  • Dorsal and anal fins have grown around
  • posterior end of fish. (Mola)
slide29

Placoid scales

Found in sharks and rays, and can vary greatly in external appearance. They do not increase in size as the fish grows, instead new scales are added. Placoid scales are often referred to as denticles.

Placoid scales consist of a flattened rectangular base plate which is embedded in the fish, and variously developed structures, such as spines, which project posteriorly on the surface. The spines give many species a rough texture.

Placoid scales of the Broadnose Sevengill Shark.

slide31

Cosmoid scales

Common to Lungfishes (family Ceratodidae) and some fossil fishes.

Similar to placoid scales (Probably evolved from the fusion of placoid scales.)

Two basal layers of bone, a layer ofdentine-like cosmine, and an outer layer of vitrodentine.

Scale becomes larger as fish grows and new bone is added to the basal layers.

Scanning electron micrograph of the cosmoid scales of a Queensland Lungfish (Krefft, 1870).

slide32

Ganoid Scales

Found in bichirs (Polypteridae), Bowfin (Amia calva), paddlefishes (Polyodontidae), gars (Lepisosteidae), and sturgeons (Acipenseridae) and some fossil paleoniscoid fishes.

Rhomboid shape with articulating peg* and socket joints between them. Actually, modified cosmoid scales with a bony basal layer, a layer of dentine, and an outer layer of ganoine (an inorganic bone salt).

*articulating peg

slide33

Cycloid and Ctenoid Scales

Found in bony fishes (the Teleostei). Overlapping = flexibility, over cosmoid or ganoid scales.

Cycloid scales—smooth posterior margin, no ctenii. (Greek "cyclo“ or circle.)

slide34

Ctenoid scales

Note: spiny posterior margins

(Greek "cteno", comb-like ctenii on the margin of the scale.)

slide35

Both consist of two main region:

surface "bony" layer (Ca2+ salts) & deeper fibrous layer (collagen).

Leads to concentric growth rings on the scale (estimate age).