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The Cartilage Fish p. 291-294. Chondrichthyes. Characteristics: - Skeletons of cartilage - Tooth-like scales ( placoid ) - Sharks, skates, rays - Replaceable teeth - First to show paired fins - Swim to maintain buoyancy (lack swim bladder). External Anatomy. Fusiform body
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The Cartilage Fish p. 291-294 Chondrichthyes
Characteristics: - Skeletons of cartilage - Tooth-like scales (placoid) - Sharks, skates, rays - Replaceable teeth - First to show paired fins - Swim to maintain buoyancy (lack swim bladder)
External Anatomy • Fusiform body • Placoidscales • Spiracles • Lateral line • Detect changes in water pressure and chemistry • Fins: • Pectoral • Pelvic • Dorsal • Caudal • Anal
Internal Anatomy • Lorenzini pores in nostril • Intestinal spiral valve • Slows passage of food for increase absorption
Fertilization • Internal fertilization • Oviparous (egg) • Oviviparous (egg hatches inside body and young born live but without placental attachment) • Viviparous (live birth) * All three found in species of sharks, skates, and rays