Skeletal System, Skin,

1
Skeletal System, Skin, Scales Chapter 3
2
Fish Skulls

• Neurocranium
• Chondocranium
• Dermatocranium
• Splanchiocranium
• Gills
• Jaws

3
(No Transcript)
4
Ethmoid Region

• Medial Ethmoid
• Lateral Ethmoids
• Vomer

5
Orbital Region

• Frontals
• Parasphenoid
• Pterosphenoid
• Orbitosphenoid
• Basisphenoid
• Infraorbitals
• Preorbitals (lacrymal)
• Postorbitals
• Suborbitals

6
Otic Region

• Parietals
• Sphenotic
• Pterotic
• Prootic
• Epiotic

7
Otic Region

• Parietals
• Sphenotic
• Pterotic
• Prootic
• Epiotic

8
Basichranial Region

• Supraoccipital
• Exocipitals
• Basiocipital
• Parasphenoid

9
Jaw Structure

• Premaxilla
• Maxilla
• Supramaxilla
• Palatine
• Dentary

10
(No Transcript)
11
(No Transcript)
12
Gill Coverings

• Preopercle
• Opercle
• Subopercle
• Interopercle
• Branchiostegals

13
Vertebral Column
14
Paired Fins
15
(No Transcript)
16
(No Transcript)
17
Soft Finned Rays
Spines vs. Rays
Rays Soft, unpointed Segmented Branched Bilateral
(lt. and rt. halves)
Spines Hard, pointed tissue Unsgemented Unbranched
Solid
18
Fins
19
Fins
20
Dorsal (medial) Fins

21
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.

22
Protocercalprimative, extends around the
posterior end (lancelets)
23
Leptocercaldorsal and anal rays joined with
caudal around posterior of fish (lungfishes,
coelocanth).
24
Heterocercalunequal lobed, vertebral column
extends into the upper portion (sharks,
sturgons, gar)
25
Homocercalequal lobes (most bony fish)
26
Isocercallast vertebrae modified (cods)
27
Gephyrocercalbridge tail Dorsal and anal fins
have grown around posterior end of fish. (Mola)
28
Scales
29
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.
30
Skin from Sharks
31
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 of
dentine-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).
32
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
33
Cycloid and Ctenoid Scales
Found in bony fishes (the Teleostei). Overlapping
flexibility, over cosmoid or ganoid scales.

Cycloid scalessmooth posterior margin, no
ctenii. (Greek "cyclo or circle.)
34
Ctenoid scales Note spiny posterior margins
(Greek "cteno", comb-like ctenii on the margin of
the scale.)
35
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).