Sharks: Form and Function

• Fins

• Pectoral fins (x2)

• Long fins on ventral side behind head on both sides of body
• Used to keep from sinking and steering

• Pelvic fins (x2)

• Close to tail on ventral (bottom) side.
• Stabilizers to prevent rolling to either side

• Dorsal fins

• 1st

• On top and behind head.
• Keep shark upright, prevent tipping

• IF there is a 2nd

• much smaller, near tail

• Anal fin

• **only on some species**
• Between pelvic fins and tail on ventral side
• Used for stability

• Caudal fin (tail)

• Moves from side to side to propel entire body forwards
• Does not allow for backwards movement

• Rostrum

• pointed snout

• Skin: Denticles

• V-shaped scales
• Reduce drag and turbulence so sharks can swim quickly and quietly
• The rough texture of the skin is referred to as shagreen

• Nostrils

• Primary sense for sharks is the sense of smell

• Sharks can detect 1 drop of blood in 25 gallons of water and from 0.25 miles away
• Rely on smell to locate prey

• Lateral lines

• Sense organ used to detect motion or vibrations in the water

• Ampullae of Lorenzini

• Electroreceptors
• Allow sharks to sense minor electrical charges caused by muscles and nerves in prey

• Nictitating Membrane

• Membrane over eye that protects when being attacked or when hunting
• Sharks do not blink
• Water surrounding eye cleans it