A second set of glands is spread evenly over the entire body and produces a thin mucus. In the water, it helps to maintain the salt and water balance in the body fluids and acts as a lubricant during swimming. These animals have enlarged back limbs to hop or jump. Most are adapted to live in dry habitats Both frogs and toads return to water to reproduce. In nearly all species, eggs are fertilized externally, and the swimming larval form that hatches from an egg is called a tadpole.
Most tadpoles are herbivorous, feeding on green algae and bacteria.
At hatching, tadpoles have a large, round body and a long tail fin. The gills are absorbed and lungs develop. The tail is absorbed. The eyelids appear. The digestive tracts and mouths of the plant-eating tadpoles change into the mouths and carnivorous digestive tracts of frogs and toads.