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tadpole,larval, aquatic stage of any of the amphibianamphibian,
in zoology, cold-blooded vertebrate animal of the class Amphibia. There are three living orders of amphibians: the frogs and toads (order Anura, or Salientia), the salamanders and newts (order Urodela, or Caudata), and the caecilians, or limbless amphibians (order
..... Click the link for more information. animals. After hatching from the egg, the tadpole, sometimes called a polliwog, is gill-breathing and legless and propels itself by means of a tail. During the period of metamorphosismetamorphosis
[Gr.,=transformation], in zoology, term used to describe a form of development from egg to adult in which there is a series of distinct stages. Many insects, amphibians, mollusks, crustaceans, and fishes undergo metamorphosis, which may involve a change in habitat,
..... Click the link for more information. it develops the lungs, legs, and other organs of the adult and, in the frog and the toad, loses the tail.
the larva of tailless amphibians. Developing from eggs, tadpoles live an aquatic life. They have external gills, a two-chambered heart, a long tail that serves for movement, an adhering organ used for attachment to underwater objects, and lateral line organs: there are no extremities. Tadpoles feed chiefly on plants.
After three or four months of development, metamorphosis takes place. The heart becomes three-chambered, breathing by means of lungs develops, a second circulatory system (respiratory circulation) develops, the gills and gill chamber become reduced, the tail disappears, and the hind legs grow greatly, becoming the basic organs for movement. The horny beak drops off, the mouth enlarges, and the intestine shortens. The sense organs also change. The middle ear chamber develops along with the drum, and the eyes acquire movable lids. The lateral line organs disappear. When these changes are completed, a small frog comes onto dry land with the fully developed extremities of a terrestrial vertebrate.