Aquatic VertebratesPART III

VERTEBRATE ZOOLOGY (VZ Lecture08 – Spring 2012 Althoff - reference PJH Chapter 6)

paddlefish

longnosegar

Arapaima

bullhead catfish

Sturgeon & Paddlefishes

Acipenseriformes: Sturgeons & Paddlefishes

• What is unique? actually lack ENDOCHONDRAL BONE

• Two extant families—so limited diversity today

• Sturgeons: 24 species, only in N. Hemisphere. Commercially important as rich flesh AND considered the best caviar…result: overexploitation. 1-6 m in length

• Paddlefishes: 2 species, one in Mississippi River valley & one in Yangtze River of China. Less dermal ossification than sturgeons. > 2m in length. American paddlefish heavily fished for caviar.

Rostum richlyinnervated with ampullary organthat apparentlyhelps to detect minute electric Fields

Planktivores in American. Carnivores inChina—almostextinct

Paddlefishes

Ostariophysi: Predominant fishes of the world’s freshwater

• Ostariophysans (characins, minnows, & catfishes)

• What is unique? Two distinct ________ characters ,

reflected in their name “bone” “bladder” (Greek)

Small bones that connect swim bladder to inner ear. Swim bladder acts as amplifier and the chain of bones as condutors greatly

enhances hearing sensitivity of these fishes. This arrangement is known as the _______________________

Result: among fishes, the most sensitive to sounds and broadest frequency range of detection

Weberian Apparatus

(present inostariophysans)

Fig. 6-11 p135 PJH

Scaphum

Claustrum Intercalarium

Tripus

Gasbladder

Ostariophysi: Predominant fishes of the world’s freshwater

• Two distinct derived characters……

Presence of fright or alarm substance in the skin: _________________________ released intowater when skin is damaged produces a fright reaction in nearby members of their own species (i.e., conspecifics) and otherostariophysan fishes

Result: fish picking up chemical signal may rush for cover or form a tighter school

Ostariophysans

• Characins (piranhas, neon tetras, and many other familiar aquarium fishes)

• Tropical fishes of American and Africa

• Carps and minnows in freshwater

• Catfishes

• Electric knifefishes

Locomotion in Water

• Swimming results from ______________________ sequential ____________ of the muscle segments along one side of the body and the _____________ _______________ of those of the opposite side.

• Most of the power for swimming comes from muscles in the posterior region of the fish

• Three types of undulatory motions of fishes:1) _______iform – highly flexible fishes2) _______iform – undulations limited mostly

to caudal region3) _______iform – body inflexible, undulation

is limited to caudal fin

Fig. 6-13 p137 PJH

Anguilliform(eel)

Carangiform(trout)

Ostraciiform(boxfish)

Undulatory Motions

• hagfishes• lampreys• most sharks• sturgeons• arawans• many catfishes• many elongate,

spiny rayed fishes

Anguilliform Carangiform

• trout• salmon• sunfishes• bass• perches• Etc.

Ostraciiform

• boxfish• trunkfishes• cowfishes

Specializations that have _______________efficiency of the different modes of swimming

• __________________

• __________________

• __________________

• __________________

Know Some

specific examples

GRAVITY

LIFT & BUOYANCY

THRUST

Fig

. 6-

15 p

139

PJH

UNDULATION OSCILLATION

Tru

nk

Cau

dal

Do

rsal

An

al

Pec

tora

l

REDUCING DRAG: Shape matters

Notice: _____________ ”design”

Drag ratios: _________________ profile of thickness

Rel

ativ

e dr

ag

Profile thickness d/l

Dire

ctio

n of

flo

w

Dire

ctio

n m

ovem

ent

Streamlined (teardrop shaped) when minimalinertial drag

a) maximum width ~ ____ of body lengthb) maximum width ~ ____ of length from

leading edge