Chondrichthyes The Cartilage Fish p. 291-294
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 Placoid scales 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
Bull Shark
Hammerhead Shark
Great White Shark
Whale Shark
Frilled Shark
Goblin Shark
Megalodon - Prehistoric
Giant Stingray
Stingray
Sawtooth
Manta Ray