Convertible Shark Teeth

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Convertible shark teeth described in Science vol. 303, p950, 13 February 2004. Sharks have sharp pointed teeth that are good for spearing fish, squid and other soft bodied prey but not very good for crunching and grinding food encased in tough shells such as crabs and lobsters. Some sharks do eat crabs and other crustaceans by grinding them up with tough plates that act like molars. The Bamboo shark has typical sharp-pointed teeth and was thought to live on a diet of fish and squid until Jason Ramsay, a student at University of Rhode Island, tossed a crab to a captive shark and watched it crunch it up. He and his supervisor then closely examined the jaws of a freshly dead specimen and discovered its teeth were attached to an elastic ligament in the jaws that enabled the teeth to fold backwards and overlap one another. When the shark’s jaws are tightly shut the two rows of folded back teeth sit squarely on one another forming a grinding surface. "This is a bit like how the jaws of herbivores work," explained Ramsay.

Ramsay and his supervisor then built a biomechanical model to see how the teeth converted from spearing to crunching mode and found it is built into the shape of the teeth. Each tooth has thick root with a small crown, creating a lever that pushes the tooth back when it is forced down hard. When the force is removed the teeth spring back up again and the shark can use them for snaring its next meal.

Editorial Comment: The structure of an animal’s teeth indicate how it eats, not what it eats. The fact that the Bamboo shark’s teeth and jaws can work like those of a herbivore reminds us that in the beginning God made all animals vegetarian. The fact that sharks eat fish, crabs and the occasional diver or surfer these days, is because sharks and the environment have degenerated following the Fall of Man and Noah’s flood. Furthermore, the fact that two intelligent scientists had to build a mechanical model to work out how these shark teeth worked indicates that it took an intelligent creator to make the real teeth. (Ref. shark, teeth, diet)

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