Sharks!

Life Science - Middle School

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Sharks! Sharks are often called fish, but are actually not in the same group (or Class) as bony fish, like a tuna or trout. They are in a Class called cartilaginous fish (or Chondrichthyes) which includes sting rays and skates. Sharks are very old and have been on Earth for millions of years. They have survived by being well-adapted for their many ocean habitats from the arctic Greenland shark to the many species prowling the tropics. Some, like the blue shark, are built like torpedoes, streamlined to reduce resistance for speed in the water. Some have color patterns that help them blend in while approaching prey. They are darker above and lighter below, like the hammerhead shark. This is a simple but effective camouflage. From above, they blend in with the dark ocean below. From below, they blend in with the lighter surface above. Others have colors and patterns that match their habitat like the sand shark’s speckled skin or the tiger shark’s dappled pattern. Sharks come in all sizes from the massive whale shark at 50 feet long and 40,000 pounds to the dwarf lanternfish a shark just six inches long. Sharks are built for hunting with rows of sharp teeth and powerful jaws, like the great white shark. Some, like the thresher shark, have long tails they use to herd fish together for feeding. Sharks find prey using a keen sense of smell that can detect blood in the water from some distance away. They can also feel the electrical field that all living things give off as we move our muscles. Thrashing prey especially attracts sharks and may explain why they sometimes mistake human swimmers for prey. Sharks eat fish, seals, rays, porpoises and even other sharks. Similar to whales, basking sharks just filter plankton and small fish out of the sea. Shark populations have shrunk to less than a quarter of what they once were because of overfishing. If the U.S. Shark Conservation Act of 2009 passes into law, it will help to save many endangered shark species from extinction. Blue Shark (10 feet long and 450 pounds) Hammerhead Shark (16 feet long and 900 pounds) Tiger Shark (17 feet long and 1,300 pounds) Great White Shark (20 feet long and 4,000 pounds) Greenland Shark (20 feet long and 2,500 pounds) Thresher Shark (20 feet long and 900 pounds) Whale Shark (50 feet long and 40,000 pounds) Amsel
94-4067 Amsel Sharks have survived by being well adapted for their many ocean habitats from the arctic Greenland shark to the many species prowling the tropics. Some, like the blue shark, are built like torpedoes, streamlined to reduce resistance for _____________________ in the water. Some have color patterns that help them blend in while approaching prey. They are darker above and lighter below, like the hammerhead shark. This is a simple but effective _____________________. From above, they blend in with the dark ocean below. From below, they blend in with the lighter surface above. Others have colors and patterns that match their habitat like the sand shark’s speckled skin or the tiger shark’s dappled pattern. Sharks come in all sizes from the massive _____________________ shark at 50 feet long and 40,000 pounds to the dwarf lanternfish, a shark just six inches long. Sharks are built for hunting with rows of sharp teeth and powerful jaws, like the great white shark. Some, like the _____________________ shark, have long tails they use to herd fish together for feeding. Sharks find prey using a keen sense of smell that can detect _____________________ in the water from some distance away. They can also feel the electrical field that all living things give off as we move our _____________________. Thrashing prey especially attracts sharks and may explain why they sometimes mistake human swimmers for prey. Sharks eat fish, seals, rays, porpoises and even other sharks. Similar to whales, basking sharks just filter _____________________ and small fish out of the sea. Shark populations have shrunk to less than a quarter of what they once were because of overfishing. If the U.S. Shark Conservation Act of 2009 passes into law, it will help to save many endangered shark species from extinction. Sharks!