Aquatic Vertebrates PART III VERTEBRATE ZOOLOGY (VZ Lecture08 – Spring 2012 Althoff - reference PJH Chapter 6) paddlefish longnose gar 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 richly innervated with ampullary organ that apparently helps to detect minute electric Fields Planktivores in American. Carnivores in China—almost extinct 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 innerear. 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 in ostariophysans) Fig p135 PJH Scaphum ClaustrumIntercalarium Tripus Gas bladder

Ostariophysi: Predominant fishes of the world’s freshwater Two distinct derived characters……  Presence of fright or alarm substance in the skin: _________________________ released into water when skin is damaged produces a frightreaction in nearby members of their own species (i.e., conspecifics) and other ostariophysan 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 fishes 2) _______iform – undulations limited mostly to caudal region 3) _______iform – body inflexible, undulation is limited to caudal fin

Fig p137 PJH Anguilliform (eel) Carangiform (trout) Ostraciiform (boxfish)

Undulatory Motions hagfishes lampreys most sharks sturgeons arawans many catfishes many elongate, spiny rayed fishes AnguilliformCarangiform 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 p139 PJH UNDULATION OSCILLATION Trunk Caudal Dorsal Anal Pectoral

REDUCING DRAG: Shape matters Notice: _____________ ”design” Drag ratios: _________________ profile of thickness

Relative drag Profile thickness d/l Direction of flow Direction movement

Streamlined (teardrop shaped) when minimal inertial drag  a) maximum width ~ ____ of body length b) maximum width ~ ____ of length from leading edge