Metamorphosing motor networks.

Many animals undergo a transition during their lifetime from a larval to an adult form, a major developmental change known as metamorphosis. This developmental process, which involves behavioural, morphological, physiological and biochemical changes, has a broad phylogenetic distribution, occurring in diverse branches of the animal kingdom, from invertebrates (molluscs, arthropods, tunicates) to certain classes of vertebrates, including amphibians (Figure 1). This phenomenon, which has fascinated biologists for centuries, remains an attractive experimental model for studying mechanisms of post-embryonic development as well as molecular mechanisms underlying hormonal regulation.