1
Odyssey Expeditions
Sharks
2
Sharks
•
Class Chrondrichthyes
-
cartilaginous skeleton
•
All are carnivorous
•
Poikilotherms
•
Rough, thick skin, Placoid
scales
•
Elongated body
•
Countershading
•
Have no swim bladder, must
swim to keep from sinking
•
Specialized sensory system
3
Shark Diversity
•
Of 300 species
known…
•
Only 10 attack man
•
Found in all ocean
environments
•
Efficient predators
•
Range in size from
4” to 30’
•
Long fossil record,
over 450 million
years
4
Hammerhead
5
White
-
tipped Reef Shark
6
Nasty Looking Sharks
7
Bottom Dwellers
8
Whale Shark
9
Shark Feeding
Mechanisms
•
Jaws and teeth
–
All are carnivorous,
feeding on plankton to
meat
–
Pelagic and some
benthic
•
Lateral line system
–
Aids in prey location
10
Eating
Machines
11
Shark Vision
•
Rods and cones
•
Moving lens for
close
-
up viewing
•
Reflective layer
behind retina
--
dim
objects (tatum
lucidum)
•
Protective
membrane covering
eye
12
Shark Reproduction
•
Internal fertilization
•
Two ways to bear
young:
–
Oviporous
•
Spotted dogfish
•
Whale shark
–
Ovoviviporous
•
Mako, thresher, sand
-
tiger: babies cannibalize
•
Hammerhead: up to forty
to fifty pups
13
More Shark Adaptations
•
Electroreception in
Sharks
–
Lateral line
-
extensive in
most sharks
–
Cephalic canal: head
region
–
Ampulae ofLorenzini:
pores in head that detect
temperature and electric
fields
•
Shark Bouyancy
–
Lack swim bladder
–
Heterocercal tail
–
Oily livers
–
Cartilage
–
Pectoral fins
•
Osmoregulation
–
Urea in bloodstream, with
special adaptation to
prevent toxicity
14
Shark Attacks?
•
Shark attacks
–
Typically 50 per year in US,
100 worldwide are
reported
–
2001, The Summer of the
Sharks?
•
What to do:
–
Watch out and get out
–
Nets, aerial spotters
–
Bang sticks
–
Blow to head, gouge eyes (?)
•
Shark stocks
–
Low reproductive
rate
–
Easily overfished
–
Highly restricted
fisheries
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