SHARKS

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SHARKS
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SHARKS
Kingdom Animalia Phylum Chordata Subphylum
Vertebrata Class Chondrichthyes 8
Orders 30 Families 350 Species
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SHARKS

• first appeared 450 my ago

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SHARKS
Iniopteryx 375 my
Belantsea 350 my
Helicoprion 345 my
Ischyodus 150 my
Stethacantus 375 my
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SHARKS

• first appeared 450 my ago
• modern forms 300 my
• many early forms became extinct w/ dinosaurs
  others evolved coincident w/ rise of mammals
  (white shark 60-65my)
• Carcharodon megalodon 50-35 my teeth 10in
  length 40

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SHARKS

• Of 350 extant species
• 82 lt 2 meters
• 50 lt 1 meter
• Avg. max length 1.5 m
• only 4 gt 4 m

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angel sharks
sawtooth sharks
dogfish sharks
cow sharks
Family Carcharhinidae (Requiem) 48 species
tiger, blue, bull , reef
Family Lamnidae (mackeral) white, mako, sand
tiger, basking
whale shark, nurse
hammerhead, bullhead
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SHARKS
Shark senses

• eyes similar to most vertebrates, size varies
  w/ habitat retinas more rod cells (dim light),
  fewer cone cells (bright light) tapetum
  (tapetal plates) nictitating membranes
• ears great accoustic sensitivity sharks
  10-800Hz (struggling fish), humans 25-1600Hz
• lateral lines - gt6,000 pits, grooves, canals
  lined w/ cilia sensitive to low freq.
  pressure waves
• nasal sacs some sharks 80 of brain devoted
  to smell
• Ampuli of Lorenzini
• teeth

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SHARKS
Great White
Sand tiger
Sand tiger
placoids (dermal denticles)
Tiger
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SHARKS
Sharks may shed as many as 30,000 teeth in a
lifetime!
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SHARKS
Why do sharks attack humans?

• mistaken identity?

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SHARKS
Why do sharks attack humans?

• mistaken identity?
• test bites?
• territoriality?
• hungry?

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SHARKS
Some shark factoids

• more humans are killed by dogs in the US each
  year than have been killed by sharks in US
  waters in the last 100 years
• 20 Great White sharks die in fishing nets off
  CA each year 0.13 humans are killed by Great
  Whites
• more people are killed by hogs in Indiana than
  by sharks in the US
• worldwide, about 3 times as many people are
  killed by elephants than sharks
• You are 6,527X more likely to die on the
  highway, 235X more likely to be killed by
  lightning, 37.5X more likely to die by snake
  bite than being killed by a shark

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SHARKS
Some shark factoids

• You are more likely to be killed by a falling
  TV than being killed by a shark
• You are 130X more likely to be killed by a
  deer than by sharks
• More people are killed each year by electric
  toasters than by sharks
• More people die by being buried in beach sand
  each year than are killed by sharks
• 6X more people are killed by ATV accidents in
  the US each year (600) than have ever been
  killed by sharks in all of US history
• More people are seriously injured in ATV
  accidents each year (125,000) than have ever
  been injured by sharks worldwide in recorded
  history

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SHARKS
Humans kill more than 100,000,000 sharks per
year, many just for their fins

So who is the more dangerous predator?