Marine Sedimentation - Odyssey Expeditions

choppedspleenMechanics

Feb 21, 2014 (2 years and 9 months ago)

115 views

1

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

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

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Bottom Dwellers

8

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


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