Sharks Class Chondrichthyes skeletons made up entirely of

Sharks

Class Chondrichthyes • skeletons made up entirely of cartilage • cartilage contains thousands of minute prisms containing mineral that strengthens bones (hydroxyapatite) • distinctive teeth, highly resistant to decay

Order Carcharhiniformes • “Ground Sharks” • nictitating eyelids present • mouth behind front of eyes • five pairs of gill slits • anal fin present

Family Carcharhinidae • head “normal” without lateral expansions • first dorsal fin originates in front of pelvic fins • anal fin trailing margin strongly concave

Tiger Shark (Galeocerdo cuvier) • snout very short, bluntly squared-off • upper lobe of caudal fin very long, sharply pointed • pigmentation pattern: dark spots/vertical bars on back and flanks

Tiger Shark (Galeocerdo cuvier) • electromagnetic receptors, Ampullae of Lorenzini • lateral line reads vibrations in water, movement of animals nearby • 2 nd most attacks on humans, behind great white

Family Sphyrnidae • head with lateral, canard-like extensions • pelvic fins triangular

Scalloped Hammerhead (Sphyrna lewini) • head, hammer-narrow and broadly arched with prominent indentations at each nare and the midline • pelvic fins triangular • first dorsal fin origin over or slightly behind pectoral axil

Scalloped Hammerhead (Sphyrna lewini) • tends to form huge schools • hammer enhances senses of smell, electroreception, lift and maneuverability • prevents 3 D vision and jaw protrusion