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FlickrAmphibians evolved from fish in the water. Now they live all over the world. Amphibians are vertebrates, or animals with backbones. In fact, amphibians were the first animals with vertebrates on land. They were ancestors of birds, reptiles, and mammals. The three main types of amphibians are frogs and toads, salamanders, newts, and toads, and wormlike creatures called caecilians. Some amphibians live on land. Others live only in the water. But most amphibians spend some time on land and some on water. Amphibians breathe through their skin and through their gills if they have them. Their skin is wet and slimy. There are more than 4,000 species of amphibians on Earth. Let’s get to know amphibians!
Activity 1 – Lifecycle
Most of the 4,000 species of amphibians lay eggs in water. The legs are covered in a goey slime. They lay many eggs at a time. Early life consists of living in water as a larva. Most amphibians grow into larvae in the first phase of life. Larvae begin with gills, breathing underwater like a fish. The larva stage can last from weeks to years, depending on the species. Frog and toad larvae are recognized as tadpoles as they swim and move around.
In the second phase, larvae develop into adults. Most amphibian species lose their gills and develop lungs for breathing, allowing them to live both on land and underwater. Different amphibian species change their structure in different ways. Some grow legs. Some lose their tail. The change from eggs to larvae to adults is known as metamorphosis. However, some amphibians are born as small adults.
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