A pond full of change

On a warm spring morning, Maia crouched beside a pond and spotted frogspawn: dozens of dark dots suspended in clear, slippery jelly. Adult frogs lay eggs in ponds. A few days later, the eggs hatched. The young animals wriggled through the water: they were tadpoles. A tadpole begins life with a long tail and gills, which help it breathe underwater. As it grows, first its back legs and then its front legs appear. Its lungs develop, and it begins to take gulps of air at the water’s surface. Its tail gradually shrinks. This series of changes is called metamorphosis. At last, the young frog can leave the water. It still needs damp places to keep its skin moist. Frogs help their habitats in more than one way: they eat insects, and they are food for some other animals. A healthy pond gives eggs and tadpoles a place to grow, so keeping rubbish and harmful chemicals out of waterways matters.