Sharks Get a Bad Rap

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After seeing motion pictures such as Jaws, Deep Blue Sea, and Open Water, many people curb their seaside activities in fear of a vicious shark attack. Indeed, the popular media have depicted the shark as an evil predator of the deep so many times that it takes extra courage to don a snorkel and vest and go to your favorite reef. But despite the shark’s reputation as a terrible killer, only 32 of the approximately 350 shark species have ever been known to attack humans. Sharks attack some 50–75 people each year worldwide, with perhaps 8–12 fatalities—far less than the number of people killed each year by elephants, bees, crocodiles, lightning, or many other natural dangers. Many people lack information about sharks, including their important role in the ocean ecosystem and their many other benefits to humans.

Sharks first appeared about 430 million years ago during the Silurian Period. They are classified in the class Chondrichthyes because their skeleton is made of cartilage. They also have jaws, paired fins, and paired nostrils. Shark habitats can range from shallow coastal areas to deep-water ocean floor habitats and even the open ocean itself. The most important aspect of sharks is their role in the marine ecosystem. As keystone predators, they help control many fish and marine mammal populations, and thus help keep the ecosystem healthy.

In addition, cultures around the world have found that nearly every part of the shark can be used: Its flesh can be eaten; the skin used as leather; the teeth made into jewelry and ornaments; oil extracted from the liver used for high-grade machine oil, vitamin A supplements, and ladies’ cosmetics; and the fins used for shark fin soup and animal treats.

Many parts of the shark have medical value as well. Its cornea has been used in eye surgery (since a shark’s cornea is similar to our own). Shark cartilage can be used to make artificial skin for burn victims. And after a rumor circulated that sharks do not get cancer, it was thought that something in the shark’s system must be a natural tumor suppressor. Thus, cancer researchers have studied sharks to determine why they are resistant to cancer in the hope of applying that information to people someday. In their search, they have settled on cartilage, the substance a shark's skeleton is made from. Each year, an estimated 100 million sharks are killed for cartilage to be used in health supplements for people seeking alternative cancer cures. As a result, the massive sale of shark cartilage has now exceeded $25 million per year, and certain species have been placed on the international endangered species list.

Questions

  1. What happens if you remove a keystone predator from a community?
  2. Do you take any health supplements? Describe them. Is there scientific evidence that these supplements do what they are reported to do?

Assignments

  1. Find out more about sharks:
    • What is their scientific classification? Are sharks related to sea bass or grouper? What animals are they related to?
    • What is a shark’s natural food source? Is there a correlation between this natural food source and shark attacks on people?

    Then interview at least 15 people about their knowledge of sharks, and report your findings. How many of these interviewees believe that sharks are fish? How many of them have shark fear, and what reason do they give for this fear?

  2. Investigate the “rumor” that sharks do not get cancer:
    • Is it true that sharks do not get cancer?
    • Which cultures use shark products for medical purposes? Is this causing over-harvesting of sharks? How many sharks are on the endangered species list?
    • What is the chemical nature of cartilage that is thought to be beneficial in cancer treatment? Have positive results from these treatments been scientifically documented?

    Then write a statement about using endangered animals for human products that may or may not work as claimed. You will need to research several practices in different cultures to write a good report.

  3. Write a conservation plan for the continued survival of sharks. Include the following topics:
    • How to change the general public’s opinion of sharks
    • The ecological value of sharks
    • The medicinal value of sharks
    • How to manage and maintain the shark population
    • How to decrease the number of shark attacks on humans.

References

http://www.realife.com

http://www.flmnh.ufl.edu/fish/sharks/isaf/graphs.htm

http://www.seaworld.org/infobooks/Sharks&Rays/home.html

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