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

• 2nd 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 3D vision and jaw protrusion