species
Post on 02-Jan-2016
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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.
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