9781422279175

above the ground. At the bottom is the spongy forest floor, littered with fallen leaves and branches.

Biodiversity S cientists have known for years that rainforests are some of the most biodiverse places on Earth, with thousands of different species. But why is it that way? That’s a trickier question. One idea is that a rainforest ecosystem is like a “cradle.” It gives birth to many different species. An-

other is that it’s a “museum,” where species simply don’t die out. Probably, it’s some of both. In either case, the rainfor- est environment is import- ant. All living things need water, and there’s plenty in a rainforest, so there’s no com- petition for this resource. It’s also warm all year long. Animals aren’t dealing with problems like freezing weath- er that could kill them.

Poison dart frogs come in colors that warn predators.

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