Aniamals, Adaptation, and the Galapagos Islands Discover with Darwin
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A Lizard Tale

Most animals get bigger as they get older. Did you know that some iguanas can make themselves smaller?

These iguanas live on the Galapagos (ga-LA-pa-goes) Islands, off the coast of Ecuador. When their food supply is low, the iguanas shrink. Why? The smaller they are, the less they need to eat.

Throughout the year, the iguanas forage, or search, for food. They eat small plants called algae (AL-jee). Sometimes, the Galapagos Islands are hit by a weather system called El Nino. This weather system brings heavy rainfall to the islands. The rainfall causes the amount of algae to decrease. The iguanas then have much less to eat. If they stayed at their normal size, the iguanas would starve to death.

Experts found that the iguanas can shrink themselves by about three inches. This always happens during the food shortages caused by El Nino. One expert, Dr. Martin Wikelski, said, "They shrink to reach a body size where they can survive."

The experts learned something else: Once the weather and food supply return to normal, the iguanas go back to their normal size!

Amazing Changes

Iguanas aren't the only animals that can change their bodies to survive. Here are some others:

Chameleon — a lizard that can change its color to blend in with its surroundings. This allows the chameleon to hide from predators.
Puffer — a fish that can inflate its body to twice its size, like a balloon. It swallows water or air to take on the shape of a ball. A puffer does this to protect itself from its enemies.

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