41 Pollywogs and Friends-Mid

Pollywogs and Friends FOCUS Question How does an amphibian's body change as it develops?

Meet the Amphibians Visit almost any pond and you might spot some odd-looking animals swimming around. They have round heads and short tails. These aren't fish. They are tadpoles, also known as pollywogs. Pollywogs are young amphibians (am-FIH-bee-unz)— animals that live part of their lives in water and part of their lives on land. Amphibians have moist skin. Some can even breathe through their skin. Frogs, toads, salamanders, and newts are all amphibians.

Amphibian Life Cycle Most amphibians begin life as pollywogs and hatch from eggs. Pollywogs live in water. As they grow, they go through metamorphosis. This means they change shape as they become adults. Most adult amphibians come out of the water and live on land. But they always go back near the water to lay eggs. The eggs must stay wet so they can hatch. Word Wise The word metamorphosis comes from the Greek language. Meta- means "change." -morph- means "shape," and -osis means a "process"

Eggs and Gills Amphibians lay eggs in ponds, marshes, swamps, or puddles. Some lay eggs that are covered with a jellylike material. The jelly helps keep the eggs safe. Others attach the eggs to underwater plants so they are hidden from animals that might eat them. In rainforests, some amphibians lay their eggs in small pools of water trapped by plant leaves. After a few weeks, pollywogs hatch from the eggs. Pollywogs have gills that let them breathe in water. Sometimes, the gills grow on the outside of their head. They look like a feathery decoration.

Eat and Be Eaten Pollywogs eat almost anything in the water. They eat water plants. They also eat dead animals. A few kinds of pollywogs have teeth. They use them to hunt for underwater insects or small fish. Many animals eat pollywogs. Fish, birds, turtles, and even large insects might try to grab one from the water. Pollywogs swim away fast by wiggling their tails. They also stay in groups to stay safe. But many are still eaten. A typical amphibian lays hundreds of eggs at one time. Only some of the pollywogs survive.

Metamorphosis The pollywogs grow quickly. After a few weeks, they start metamorphosis. Pairs of legs begin to grow out of their body. In some amphibians the tail gets shorter and shorter. But in others, the tail remains into adulthood. The pollywogs also grow lungs. Now they begin to breathe air. After the legs and lungs are fully developed, the adults can come out of the water. The animals move around on land.