L3 - Postcranial Morphology

Fusiform, tapers from the midpoint, strong swimming

Compressiform, laterally compressed,  vertical disc, trick question these include flatfish

Depressiform, dorsoventrally depressed

Anguilliform, eel like/elongated bodies

Filiform,extreme eel like/elongated

Globiform, opposite of elongation, basketball/globe shape

stuff in Postcranial Skeleton

Vertebral column, Caudal complex

stuff in Vertebral Column

Precaudal vertebrae, Caudal vertebrae

Precaudal vertebrae

Vertebral column:  first set behind head all the way to the edge of body wall (majority of internal organs)

Caudal vertebrae

Vertebral column: all the way to the caudal fin, single spin called the haemal spine

Features of individual vertebra

Centrum, Neural spine, Pleural ribs (precaudal), Haemal spine (caudal)

Centrum

individual vertebra: Disc-shaped central part of vertebra

Neural spine

individual vertebra: Projects dorsally/top from centrum, Neural arch at base (houses the spinal cord)

Pleural ribs

individual vertebra: precaudal, Paired, ventral/bottom projections, Protect body cavity

Haemal spine

individual vertebra: caudal, Single, ventral/bottom projection, Haemal arch at base (contains caudal artery, in caudal/tail end section)

bones for Caudal Fin Complex

modified vertebral elements and fin rays, Urostyle, Epurals, Hypurals

Urostyle

Caudal Fin Complex: final part to vertebrate, made of fused vertebrae

Epurals

Caudal Fin Complex: Modified neural spines

Hypurals

Caudal Fin Complex: Flattened haemal spines associated with the urostyle

Principal caudal fin rays

 from base of caudal fin to posterial/end

Procurrent fin rays

 do not reach the very end, the very tiny short ones that fall at the edge of the tails

Main Caudal Fin Types

Protocercal, Heterocercal, Homocercal

Protocercal

“Primitive”, undifferentiated fin, in ancient lineage lampreys and larvae fishes

Heterocercal

 unequally sized lobes, upper lobe larger, like sharks

Homocercal

most common,equal lobe

homocercal tails variants

Less Common Caudal Fin Types

Diphycercal/Leptocercal, Isocercal, Hypocercal, Gephyrocercal

Diphycercal/Leptocercal

three lobed appearance, coelacanths

Isocercal

 flattened plate is a flattened vertebrae instead of spine, in cod

Hypocercal

opposite of heterocercal, lower lobe larger than upper

Gephyrocercal

sunfish only, not true caudal fins, Dorsal and anal fin form a bridge tail

Appendicular Skeleton: Pectoral Girdle & Fin from skull

Posttemporal, Supracleithrum, Cleithrum, Radials, Fin Rays

Posttemporal

 for skull articulation, two prongs/processes (any structure with elongated pointed end, sticks out from main structure

Supracleithrum

Forms joint with posttemporal for cranial rotation during feeding

Cleithrum

largest bone in pectoral girdle

Radials

at base of fin, support fin ray

Fin Rays

Flexible supports for pectoral fins (fins on side)

Pelvic Girdle Bones

Basipterygium (bpt)

Basipterygium (bpt)

large structure at back of fin where pelvic fin attaches, for modern fishes basipterygia and radials become fused or lost

Shark and Skates

male shark, modified pelvic structures (claspers)

Skates use modified pelvic fins to walk

Appendicular Skeleton evolutionary trends

pelvic fins (purple) move from back to front, pectoral fins (blue) move ventral/bottom of body to up and to the side

how clingfish work

Pelvic & Pectoral girdles work together as a suction disc (hair for friction)

Median Fins: Dorsal & Anal

Dorsal & Anal Fin, Pterygiophores (Pt), Lepidotrichia

Dorsal & Anal Fin

can have spines (rigid, unsegment), soft rays (soft, segment) or combo, vary in number of dorsal fin

Pterygiophores (Pt)

Internal supports of dorsal & anal fins

 base for spine/ray for muscle to attach to and raise fin up/down

Pterygio- (wing) -phores (carry)

Lepidotrichia

Bony elements of fin rays in bony fishes, “ceratotrichia” when made of cartilage, part of the soft rays (the individual segments)

Lepido- (scale) -trichia (hair)

Finlet

in tuna, between dorsal and anal fin, for open water control

Adipose fin

Small fin behind dorsal fin supported by cartilage (not really fatty), seen in salmon

Parts of muscles

Myomeres, Epaxial muscles, Hypaxial muscles

Myomeres

how muscles are organized in segments, w shaped, allows body to sway back and forth

Epaxial muscles

Located dorsally/up

e-(above)

Hypaxial muscles

Located ventrally/bottom

hy-underneath

Flexors - Extensors

 main muscles, contract/relax to sway body left/right for tail

Protractors - Retractors

individual rays and spines to protect up, retract down in body, spread/close median fins (unpaired dorsal/bottom fin)

Adductors - Abductors

for paired fins, movement towards (Add d for move limb down)/away body (like take away)

Placoid Scales

sharks and relatives, teeth like and small, don't grow in size

Cosmoid Scales

 extinct and fossil and lungfishes/coelacanths, thick plating

Ganoid Scales

 highly ridged, armor like with enamel coating so looks shiny, sturgeons and gar

Leptoid Scales

 most fishes, thinnest on average, single thin layer of bone, four types

Leptoid: cycloid

Leptoid: crenate

like a crater

Leptoid: ctenoid

k/cten- (comb)

Leptoid: spinoid

spines

Lateral Line

Lateral line scales are modified to allow water to flow past internal sensory structures (neuromasts)

Scales: Scutes

modfieid into scutes or spines