Another creature many countries eagerly introduced to their homelands is the cane toad, a native of Venezuela and Guyana [source: Butler]. Like the European starlings, cane toads chow down on a lot of insects that can ruin sugarcane and other valuable crops. But these gigantic amphibians -- which can grow up to 15 inches (38.1 centimeters) long -- will eat almost any terrestrial animal, and fight with native amphibians for food and breeding grounds. Even worse, cane toads excrete a strong toxin from their skin that can sicken or kill domestic animals and wildlife, and even humans. People have died from eating the toads and their eggs, too [source: ISSG, WebEcoist].
Cane toads are especially problematic in the U.S. and Australia. In the latter country, some feel eradication is impossible because the toads' numbers are so great. One Queensland researcher is working on developing a strain of cane toad that can only give birth to males, ensuring the creatures' eventual demise, once the genetically engineered toads mate with regular ones [source: IMB - Institute for Molecular Bioscience]. However, only time will tell whether the cane toad or man is more resourceful -- and if we've finally learned our lesson about introducing non-native species into our homelands.
Author's Note: 5 Invasive Species That Might Conquer the World
When I was a kid, there was a popular sketch on "Saturday Night Live" about the killer bees that were coming to invade North America from the Southern Hemisphere. They reached America some 12 years after the sketch ran, and are entrenched in several southern states today, where they're causing agricultural turmoil -- although not mass murder, as some feared. Unfortunately, invasive species are a problem worldwide. I'm sure you all can quickly cite some of the problem plants, insects, birds or mammals in your own backyard. Just keep that in mind if you're ever tempted to buy an exotic pet, or plant a pretty -- but non-native -- plant in your backyard that's known to quickly spread. If we're all more watchful, we can help combat this problem.
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Seed banks literally 'bank' seeds for our future. But a new study found not all seeds can be properly stored. HowStuffWorks looks at what this means.