Thyroid Hormones and Amphibian Metamorphosis

Abstract

THE BODY FORMS of many animals change dramatically during development from the larval to the adult stages. Most dramatic, of course, is the change of a caterpillar to a butterfly or moth. This change in body form and function is referred to as metamorphosis. Some vertebrates also undergo an equally dramatic change in body form and life style. Most aquatic amphibians hatch from eggs and spend the initial stages of their life as swimming larvae after which they metamorphose into frogs, toads, or salamanders. This transition from an aquatic to a terrestrial environment requires a large number of physiological and morphological changes. The larvae must