Marine Sedimentation - Odyssey Expeditions

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Odyssey Expeditions


Sharks



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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

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Shark Diversity

•
Of 300 species
known…

•
Only 10 attack man

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Found in all ocean
environments

•
Efficient predators

•
Range in size from
4” to 30’

•
Long fossil record,
over 450 million
years

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Hammerhead

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White
-
tipped Reef Shark

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Nasty Looking Sharks

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Bottom Dwellers

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Whale Shark

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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


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Eating
Machines

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Shark Vision

•
Rods and cones

•
Moving lens for
close
-
up viewing

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Reflective layer
behind retina
--
dim
objects (tatum
lucidum)

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Protective
membrane covering
eye

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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

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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


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Shark Bouyancy

–
Lack swim bladder

–
Heterocercal tail

–
Oily livers

–
Cartilage

–
Pectoral fins

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Osmoregulation

–
Urea in bloodstream, with
special adaptation to
prevent toxicity

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Shark Attacks?

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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

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Nets, aerial spotters

–
Bang sticks

–
Blow to head, gouge eyes (?)


•
Shark stocks

–
Low reproductive
rate

–
Easily overfished

–
Highly restricted
fisheries