Ciona intestinalis. (a) The Ciona adult develops from a tadpole larva by a dramatic metamorphosis, during which it resorbs its tail, modifies its central nervous system, and transforms its digestive system into incurrent and excurrent siphons that filter plankton through perforations in the pharynx (gill slits). Image courtesy of Andrew Martinez. (b) An early tadpole hybridized with a probe for the alcohol dehydrogenase gene CiAdh3 to show the anterior endoderm . Chordate features such as the notochord and the muscular tail are visible, and the positions of the sensory vesicle (brain) and dorsal nerve cord are indicated. (c) Electroporation is an efficient procedure by which to introduce DNA into Ciona for functional experiments, as is shown in this larva expressing a reporter construct made by Corbo et al. , a lacZ gene driven by the brachyury promoter in the notochord.