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  1. 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. nature_conservation/grey_nurse_shark.jpg
  2. 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 http:// but lie in a row behind the head. sharks/Image15.gif 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 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. 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 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. 4. november,5 2009 by abigail wright period 5 academic biology SH ARK S References: