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Recommended for: Grades 6-8

Resource: Crocodiles! Clickable Croc

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This interactive feature from the NOVA "Crocodiles!" Web site details some of the physical and behavioral characteristics that have enabled crocodiles to survive and thrive for 200 million years -- despite the environmental conditions that drove the dinosaurs to extinction.

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Teachers' Domain, Crocodiles! Clickable Croc, published September 26, 2003, retrieved on ,
http://www.teachersdomain.org/resource/tdc02.sci.life.reg.clickcroc/

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In the animal kingdom, crocodiles are the consummate survivors. Having arisen some 200 million years ago, they have outlived the dinosaurs by some 65 million years. Given their longevity, it is clear that crocodiles were well adapted not only to the environment in which the dinosaurs flourished, but also to some dramatically different conditions since then. The fossil record tells us that ancient crocodiles looked nearly identical to crocodiles living today. Somehow crocodiles survived the event that caused the dinosaur extinction, and continue to thrive in spite of more recent human-induced changes in the environment that have caused countless other species to become extinct.

Biologists attribute the success of crocodiles, at least in part, to their ability to withstand incredible bouts of starvation. In fact, it is not uncommon for crocodiles to go without food for an entire year. Though under such conditions they become desperately thin, they remain active and capable of feeding whenever the opportunity arises. Their ability to do this owes a lot to their cold-bloodedness. Warm-blooded animals burn up to 80 percent of the calories they eat simply maintaining their body temperature. Crocodiles have no such requirement, and this may explain their ability to survive through difficult times.