Sharks have existed for over 350 million years and are apex predators at the top of the ocean food chain. They have adapted to thrive in the ocean through streamlined bodies that allow powerful swimming. Sharks are mostly carnivorous but some species are filter feeders. They reproduce through internal fertilization and either live birth or egg laying. Sharks have adapted various senses like electroreception and a lateral line to detect prey and movement in the water. Although some species are threatened, sharks play an important role in maintaining ocean ecosystems.

1. november,5 2009 by abigail wright period 5 academic biology
SHARKS
u n d e r w a t e r
w a r r i o r s
Sharks have existed for over 350 million years, even before the time of the dinosaur. Thankfully,
unlike the dinosaur they adapted and were able to thrive even until today’s time. Although they are
mostly feared by humans, I like to look at sharks as the misunderstood gentle giants of the sea. Now let
me tell you about their life, their history, and how they operate as a species.
Internal and External Transport: Sharks have a streamlined body and use their fins to move
them. They can only drift way from objects directly in front of them because their fins do not allow
them to swim backwards. Their tail has a large upper lobe which allows power for slow cruising or
sudden bursts of speed. Internally, a sharks vertebra column extends into the dorsal portion, which
allows greater surface area for muscle attachment which provides greater locomotion.
Nutrition: Most sharks are carnivores, although some species will eat anything, Whale, Basking,
and Megamouth sharks use filter feeding to eat plankton. Although many people are afraid of sharks as
they are afraid to be eaten, most species of sharks seek particular prey and rarely stray from what they
prefer. In order to find prey, they use their electroreceptors located on the under side of their mouths.
Reproduction: Sharks practice internal fertilization and they either have a live birth or lay eggs.
In order to do this, male and female sharks swim parallel to each other and will often bite to display
interest. Sharks are K-selected reproducers, which means they produce a small number of well
developed young opposed to a large number of poorly
developed young.
http://www.epa.gld.gov.au/images/
nature_conservation/grey_nurse_shark.jpg

2. november,5 2009 by abigail wright period 5 academic biology
SH ARK S
Response to Stimuli: do not have this membrane but go into fresh water by excreting
Sharks use Electroreception instead roll their eyes backward. salt through their anal gland.
through an organ called the Sharks also replace their teeth General Structure:
Ampullae of Lorenzi. they use regularly as they are not attached
them to detect the to any skeletal element of the jaw.
Respiration: Sharks extract
oxygen from seawater as it passes
over their gills. Unlike other bony
http://
fish, shark gill slits are not covered www.bio.miami.edu/
http://
but lie in a row behind the head. sharks/Image15.gif
en.wikipedia.org/wiki/ Sharks have a skeleton made of
electromagnetic fields that all Behind the eye lies the spiracle
cartilage and connective tissue, it
living things produce. They also that assists in water intake during
is more flexible, durable, and has
use them as navigation as the respiration and plays a major role
half the density of bone. They
ocean currents use the magnetic in bottom dwelling sharks as they
have tooth-like scales that cover
field of Earth to move in the way cannot pump water through their
their body called placid scales
they do. Also, they use the gills and rely on constant
which make a shark very rough.
Lateral Line which detects motion swimming to force water through
They have 5-7 gill slits without
or vibrations in water, mainly the gills/mouth which is called
covers and have eyes without
used to detect movements of ramjet ventilation.
eyelids which are protected
other animals in the water, Regulation: Sharks are cold-
instead with a protective covering.
especially wounded fish. Sharks blooded. They do not drink water
Place in food chain:
can sense frequencies in the range as they are extremely salty and
Hammerhead and Great White
of 25 to 50 Hz(Hertz, complete contain more salt that the sea
cycles per second) which is known as being
Adaption: Sharks have hyperosmotic. Sharks contain the
adapted their eyesight. They can minerals urea, trimethalamire
contract and dilate their pupils asoxide, and other salts. They stay
they wish. They have a protective hydrated by absorbing pure water
covering called a nictitating from the sea by the process of
http://www.sullacrest.it/squalo/
membranes which protect their osmosis. This in itself makes GreatWhiteShark920jpg
eyes from being attacked or when sharks unable to live in fresh Sharks are at the top of the
they are attacking prey. On the water. Only a selected number of underwater food chain and
other hand, Great White Sharks sharks can lower their salt level to known as apex predators. Apex

3. november,5 2009 by abigail wright period 5 academic biology
SH ARK S
meaning at the top of something.
Background of group: Sharks have existed on Earth for more than 350 million years, although
fossils of them are quite rare as they are made of cartilage rather than bone.
What “Oddball” exists?: The Whale Shark, which is the largest living fish species is a filter feeder,
unlike most of the other sharks.
Other Organisms found in group: Chimaeras, Skates, and
Rays.
Type of Symmetry: Sharks have bilateral symmetry which
means that you can cut it in half and both sides will look the
same.
Extinct or Endangered?: Sharks are under serious threat from
fishing and other human activities.
Importance to our lives: Sharks keep the fish population
down so they are not overpopulating the oceans.
Any other additional facts: Until the 16th century, sharks
were known as “sea dogs”. Sharks do not have swim bladders for
buoyancy, instead they have a large liver filled with oil that
http://aquaviews.net/wp-
contains squalone. The liver of a shark is up to 30% of its body
content/uploads/2009/07/jpg
mass, it will employ dynamic lift to maintain depth and then sink
when they stop swimming.

4. november,5 2009 by abigail wright period 5 academic biology
SH ARK S
References:
www.enchantedlearning.com/subjects/sharks/classification/extinct.shtml
http://www.bio.miami.edu/sharks/shark.htm
http://en.wikipedia.org/wiki/Shark
http://enchantedlearning.com/subjects/sharks/anatomy/diet.shtml