Shark Information
Last Updated 11/26/2007
Shark Information
Last Updated 11/26/2007
Evolution
400-350 mya
Unchanged for the past 70 million years
First fully jawed vertebrae
Survived four global mass extinctions where 80% of life wiped out.
Evolved from placoderm (primitive jawed fish)
370 kinds of sharks
Rare to find fossil fins; cartlege decomposses, human skullks have no ears or nose
Anatomy
No swim bladder
Shark is like an airplane, fins as wings
Liver has so much oil that the shark is bouyant
3000 teeth; 6-20 rows; 20,000 in a lifetime
Respiration
No gill cover; can't pump water; move or get into current
Reproduction
Some lay eggs in egg pod and attach it to kelp.
Some give birth to live young.
Sharks can have 2-136 pups.
Mother will eat them if she catches trhrm.
Long gestation period: 14 months
Skin: Placoid Scales
Sandpaper texture
Look like small shark teth
Teeth evolved from scales
Used in purses, shoes, boots, and wallets
Habitat
Benthic: bottom
Pelagic: top
Sub-tidal: shallow
Esturine: inlets
Size
Whale Shark, 40-60 ft, 26,000 lbs; harmless, filter feeder
Dangerous Sharks
Great White
Bull
Tiger
Whiptail
All 20 ft and 5000lbs,
Shallow water
30% fatal