Amphibians are vertebrates of the taxonomic class Amphibia including animals such as frogs and toads (order Anura), salamanders (order Caudata), and caecilians (order Gymnophiona). Thought of as cold-blooded, amphibians are ectotherms, meaning they are unable to regulate their own body temperature independently of the temperature of their surroundings. Amphibians are generally small with thin skin permeable to air and water. With few exceptions, amphibians do not actively care for their young. In general, amphibian reproduction strategy consists of egg-laying and external fertilization of a large number of eggs in a moist or fully aquatic environment. Fertilized eggs develop into amphibian larvae that live part of their lives dependent on an aquatic environment requiring gills and specialized feeding habits. Following a pattern of development unique to amphibians, amphibian larvae undergo marked changes and metamorphose into a terrestrial form that lives on land. Typically, this metamorphosis is demonstrated by loss of gills, changes in overall appearance, and changes in diet.Amphibians live in diverse habitats, often in large numbers, and play several important ecological roles. As consumers, amphibians help regulate populations of the organisms they consume, chiefly invertebrates. As prey items, amphibians are consumed by a variety of larger predators such as reptiles, birds, mammals, fish, predatory invertebrates, and other amphibians. When consumed by larger predators, amphibians transfer the energy and nutrients from amphibian prey items such as small invertebrates to larger predators.