Sharks Powerpoint - Teacher Notes

Document Sample
Sharks Powerpoint - Teacher Notes Powered By Docstoc
• 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
• Sharks are cartilaginous fish

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

• Sharks teeth are NOT attached to their

• Teeth range from needlelike to large flat
• 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
                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
                 • They can detect
                   amounts of blood as
                   small as 1 ppm. (part
                   per million)

                 • Rely on sense of
                   smell to locate prey
            Locating Prey

Lateral lines           Electro-receptors
  Sense organ used to      Allow sharks to
  detect motion or          sense minute
  vibrations in the         electricity caused
  water                     by muscles and
                            nerves in prey
• 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
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
              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

  – 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
• 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
                 • Tiger sharks devour
                   their entire prey when

• Tiger sharks have become a problem in
• 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
               Why attack?
• Mistaken Identity:
  – Shark mistakes a person in the water as a
    seal when looking from below the waters

• 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

• Scientists unsure why
  this phenomenon
           Avoiding an Attack
• Avoid water during darkness or twilight hours
• Do not enter water if bleeding from an open
• Do not wear shiny jewelry – resembles fish
• 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

• 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

Shared By: