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Some plants get so hungry they eat flies， spiders， and even small frogs. Whats more amazing is that these plants occur naturally （in special environments） in every state. In fact， theyre found on every continent except Antarctica. Youve probably seen a Venus flytrap. Its often sold in museum gift stores， department stores， and even supermarkets. A small plant， it grows 6 to 8 inches tall in a container. At the end of its stalks（茎）are specially modified leaves that act like traps. Inside each trap is a lining of tiny trigger（触发）hairs. When an insect lands on them， the trap suddenly shut. Over the course of a week or so， the plant feeds on its catch. The Venus flytrap is just one of more than 500 species of meat-eating plants， says Barry Meyers-Rice， the editor of the International Carnivorous Plant Societys Newsletter. Note： Despite any science-fiction stories（科幻小说）you might have read， no meat-eating plant does any danger to humans. Dr. Meyers-Rice says a plant is meat-eating， only if it does all four of the following： attract， kill， digest， and absorb some form of insects ， including flies， butterflies， and moths. Meat-eating plants look and act like other green plantswell， most of the time. All green plants make sugar through a process called photosynthesis（光合作用）。 Plants use the sugar to make food. What makes meat-eating plants different is their bug-catching leaves. They need insects for one reason： nitrogen（氮）。 Nitrogen is a nutrient that they cant obtain any other way. Why Almost all green plants on our planet get nitrogen from the soilMeat-eating plants cant. They live in places where nutrients are hard or almost impossible to get from the soil because of its acidity（酸度）。 So theyve come to rely on getting nitrogen from insects and small animals. In fact， nutrient-rich soil is poisonous to meat-eating plants. Never fertilize（施肥）them！ But dont worry， either， if they never seem to catch any insects. They can survive， but theyll grow very slowly. | 
