Species There are over 360 species of sharks! They can range in size from small enough to fit in your hand to up to 46 feet!! Smallest Shark is the Pygmy.

Species• There are over 360 species of sharks!

• They can range in size from small enough to fit in your hand to up to 46 feet!!

• Smallest Shark is the Pygmy Shark

• Largest Shark is the Whale Shark

– Filter feeder, feeds on plankton

Skeleton

• Sharks are cartilaginous fish

• Skeleton made of cartilage which is lighter and more flexible than bones

Respiration• Sharks have uncovered gills used for

respiration

• Extract oxygen as water passes over the gills

• Most species of shark can pump water over their gills for when they are not moving using the spiracle

• A small percentage of sharks need to stay in constant motion to respire

Teeth

• Sharks teeth are NOT attached to their jaws

• Teeth range from needlelike to large flat teeth

• Teeth are grown and replaced often

• Sharks have multiple rows of teeth

• Sharks can have about 25,000 to 30,000 teeth in one lifetime

• Some replace teeth every

8-10 days, others every few

months

Life Span• Lifespan varies by species

• Most live about 20 – 30 years

• The spiny dogfish can live up to 100 years

• It is thought that the whale shark can live over 100 years as well

Sense of Smell• Incredible sense of

smell

• They can detect amounts of blood as small as 1 ppm. (part per million)

• Rely on sense of smell to locate prey

Locating Prey

Electro-receptorsAllow sharks to

sense minute electricity caused by muscles and nerves in prey

Lateral linesSense organ used to detect motion or vibrations in the water

Vision

• Sharks have eyelids but do not blink

• Water surrounding eye cleans it

• Sharks have a membrane over eye that protects when being attacked or during predation

• Great White Sharks roll eyes back when attacking

Do Sharks Sleep??

• Scientists unsure!!

• Possible they sleep in a similar manner to Dolphins

– Half the brain sleeps at a time

Shark Attacks

• 2000 - 79 attacks, 11 fatalities

• 2005 - 61 attacks, 4 fatalities

• 2006 - 62 attacks, 4 fatalities

• Majority occur in the United States

• More people die from lightning strikes each year

Sharks Involved

• Three types of sharks have been involved in a significant amount of attacks– Great White– Tiger Shark– Bull Shark

Great White Shark• Great Whites are generally about 13-16 ft

and weigh 1500 - 2450 lbs

• Found in waters between 54 and 75 degrees F

• Countershading

– White underside and gray dorsal side

– Difficult to see when looking at horizontally

– When seen from above, gray blends in with the water

– When seen from below, white blends in with surface of water

Typical Prey• Sting rays, tuna, smaller sharks, dolphins,

seals, sea lions

• Shark attacks most often occur in the morning, within 2 hours after sunrise

• Hard to see a shark close to the bottom

• Attack from below at fast speeds

Tiger Sharks• Average 11 feet and 850 - 2000 lbs

• Commonly found around islands in the central Pacific

• Dark spots and stripes are prominent in young sharks and fade as the shark matures

Hunting Habits• Teeth can bite through

bone and turtle shells

• Known to circle its prey and even study it by prodding it with its snout

• Tiger sharks devour their entire prey when attacking

Hawaii

• Tiger sharks have become a problem in Hawaii

• Hunted to help control attacks, but no decrease occurred

• Considered sacred by native Hawaiians

Bull Shark

• Dwell in shallow water, possibly posing highest threat to humans

• Can tolerate freshwater

• Males: 6.8 ft, about 200 lbs

• Females: 11.5 ft, about 700 lbs

Hunting Habits

• Bump and Bite Technique

• Shark circles prey often bumping them before the actual attack.

• They are extremely territorial and will attack other animals that enter their territory.

Why attack?• Mistaken Identity:

– Shark mistakes a person in the water as a seal when looking from below the waters surface

• Curiosity

• Sharks typically bite once and then swim away

• Explanations:

– Humans do not taste like their typical prey

– Return to the prey after it exhausts itself

Dolphin Protection• Sharks will not attack

when dolphins are around

• Scientists unsure why this phenomenon occurs

Avoiding an Attack

• Avoid water during darkness or twilight hours

• Do not enter water if bleeding from an open wound

• Do not wear shiny jewelry – resembles fish scales

• Avoid areas near commercial fishing

• Avoid murky waters

• Do not splash a lot

Fending off an attack

• Hit back in sensitive areas such as the eyes and gills

• Shows shark you are not defenseless

Hammerhead Shark• Habitat: Shallow tropical and warm temperature waters

• Diet: Stingrays, Other small sharks, fish, crustaceans

• Size: 12 - 20 ft.

• Attacks: 18 (0 fatal)

• Hammerheads have small mouths and seem to do a lot of bottom-hunting. (Stingrays!)

• Their wide-set eyes give them a better visual range than most other sharks.

• They are also known to form schools during the day, sometimes in groups of over 100.