SHARKS DOLPHINS | SHARKS | WHALES
Out of all the species walking, flying, slithering or swimming, there aren't many who have been around as long, survived as well, or come in so many shapes and kinds as the shark. The earliest evidences of sharks are isolated spines, teeth and scales that appeared about 430 million years ago in the Silurian Period, known as the "Age of Fishes". Sharks have a sleek, streamlined design which helps them swim without using up a lot of energy.They certainly need to conserve their energy because they never really sleep and most of them never stop swimming.
Until the 16th century, sharks were known to mariners as "sea dogs". The etymology of the word "shark" is uncertain. One theory is that it derives from the Yucatec Maya word xok, pronounced 'shok'. Evidence for this etymology comes from the OED, which notes the name "shark" first came into use after Sir John Hawkins' sailors exhibited one in London in 1569 and used the word "sharke" to refer to the large sharks of the Caribbean Sea.
Sharks are a group of fishes characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (or Selachii), and are the sister group to the rays. However, the term "shark" has also been used for extinct members of the suborder Elasmobranchii outside the Selachimorpha, such as Cladoselache and Xenacanthus. Under this broader definition, the earliest known sharks date from more than 420 million years ago.
Some sharks are fierce predators, and would be happy to eat you if they encountered you. Almost any shark six feet or longer is a potential danger, but three species have been identified repeatedly in attacks: the Great White Shark, the Tiger Shark and the Bull Shark . All three live world wide, reach large sizes and eat large prey such as marine mammals or sea turtles. But most sharks never grow longer than five feet and never even see anyone with legs and arms anyway. People kill thousands more sharks every year than sharks kill people.
Sharks take about as long to mature as we do. Some of them become adults in their teens. A mother shark carries her babies inside her body while they develop, sometimes for more than a year. Even so, some sharks are born inside an egg which they have to crack open. They spend early portions of their lives in nursery grounds. Some of the advantages sharks have over people is that they keep growing new teeth, they don't have breakable bones, and they are not prone to get cancer. Sometimes sharks are referred to as swimming computers because of the six senses which they possess: vision, hearing, vibration, smell, taste and electro-perception.
The great white shark, Carcharodon carcharias, also known as the great white, white pointer, white shark, or white death, is a large lamniform shark found in coastal surface waters in all major oceans. It is known for its size, with the largest individuals known to have approached or exceeded 6 metres (20 ft) in
length, and 2,268 kilograms (5,000 lb) in weight. This shark reaches maturity at around 15 years of age and can have a life span of over 30 years.
Sharks belong to the superorder Selachimorpha in the subclass Elasmobranchii in the class Chondrichthyes. The Elasmobranchii also include rays and skates; the Chondrichthyes also include Chimaeras. It is currently thought that the sharks form a polyphyletic group: some sharks are more closely related to rays than they are to some other sharks.
Shark teeth are embedded in the gums rather than directly affixed to the jaw, and are constantly replaced throughout life. Multiple rows of replacement teeth grow in a groove on the inside of the jaw and steadily move forward in comparison to a conveyor belt; some sharks lose 30,000 or more teeth in their lifetime. The rate of tooth replacement varies from once every 8 to 10 days to several months. In most species, teeth are replaced one at a time as opposed to the simultaneous replacement of an entire row, which is observed in the cookiecutter shark.
England Aquarium http://www.neaq.org/
Shark Specialist Group
Marine Laboratory: The Center for Shark Research http://www.mote.org/~rhueter/shark_research.phtml
Pelagic Shark Research Foundation http://www.pelagic.org/
Shark Myths http://www.marinelab.sarasota.fl.us/~rhueter/sharks/myths.phtml
This site, also created by Mote Marine Laboratory, debunks common shark myths with the help of witty cartoons.
Costa Rica! http://www.costarica.com/
The official Web site for the country, this rich site offers detailed information on everything from adventure travel to business opportunities. Click here for the Embassy of Costa Rica as well.
The Undersea Hunter http://www.underseahunter.com/
This thorough site gives you everything you'd ever want to know about the Undersea Hunter, the live-aboard dive boat on which this expedition is based at Cocos Island.
Cocos Island Research Center http://www.istmo.com/cocos/index.html
Secrets of the Ocean Realm http://www.pbs.org/oceanrealm
This Web site, which accompanied the acclaimed PBS series of the same name, features an interview with Howard and Michele Hall on the challenges of underwater filmmaking.
Island | Sharkmasters
| World of
Sharks | Dispatches
The Shark Research Institute Web Site
The Shark Research Institute (SRI), a multi-disciplinary non-profit 501(c)(3) scientific research organization, was created to sponsor and conduct research on sharks and promote the conservation of sharks. Founded in 1991 at Princeton, New Jersey, USA, SRI has field offices in Canada, the Galapagos Islands, Honduras, Mexico, South Africa and the Seychelles. A new data collecting site has been established in Australia.
SRI works with the scientific community, individuals and organizations concerned about the health of our marine ecosystem, and marine resource users: subsistence fishermen, sport divers, and the dive tourism industry. SRI works to correct misperceptions about sharks and stop the slaughter of 100 million sharks annually. A primary goal is creating value for sharks as sustainable natural resources for the dive tourism industry, particularly in developing countries. By so doing, a steady revenue stream is also generated for local fishers that might otherwise slaughter the sharks for immediate gain. Current programs involve visual and satellite tracking, behavioral and DNA studies of sharks, environmental advocacy, publications and public education.
Island of the Sharks Site Map
is Cocos, This is Cool" (Oct. 19)
Questions and responses
Who of Sharks
Caribbean Hotels - sharks page
Top 20 Shark Facts Presented by the Discovery Channel
Basic Facts About Sharks From the Defenders of Wildlife
National Geographic Presents: Animals—Whale Shark
Whale Shark Facts by See the Wild
National Ocean Services Reports That In General, Sharks Do Not Eat Humans
Island of the Sharks Presents Shark Bytes
Sand Tiger Shark by New York Aquarium
Bull Shark (Carcharhinus leucas) by Shark Foundation Hai-Stiftung
Kid Zone Presents Types of Sharks
Shark Species Introduction by Shark Savers
Oceana Presents Sharks: Overview
The Great White Shark, Presented by the University of California Museum of Paleontology
Marine Bio Presents Great White Sharks, Carcharodon carcharias
Tiger Shark Photos, By the Florida Museum of Natural History
Museum Victoria Presents Sharks
Shark Research Committee Presents Save the Sharks, Save the Oceans
Project AWARE Presents Researching the Shark Fin Trade
Project Oceanica Presents Satellite Tagging of Oceanic Sharks and Billfishes on the Charleston Bump
Department of Fish and Game Presents White Shark Tagging off Cape Cod
Tagging Sharks a Chilling Task, By the Honolulu Advisor
US New Presents Shark Attacks: Worry More About Lightening or Bees
The Humane Society of the United States Presents Shark Conservation Act Wins Final Congressional Approval
The Pelagic Shark Research Foundation Presents Open Water: The Monterey Bay/Marine Canyon Pelagic Shark Tagging Project
City of Cape Town Presents Shark Safety Tips
Shark Safety by the National Geographic Channel
Q & A on Shark Safety by ABC News
Town of Cottesloe Presents Beach Conditions and Shark Safety
Shark Safety Tips By the Palm Beach Post News
Shark Safety Tips By BBC Newsround
Sharks Quiz, Presented by Oracle Thinkquest
The Great White Shark Quiz, Presented by Channel One News
Discovery Education Presents Lesson Plan Library: Sharks
Shark and Cultural Educational Resources, By the Monterey Bay Aquarium
Grades 11-12 Shark Lesson Plans, By the Atlantis Marine World
Whale Shark Word Search by the Georgia Aquarium
Find the Sharks, by Exploring Nature Educational Resource
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