An ascidian - Ciona intestinalis. (a) Phylogenetic relationships of chordates. Ascidians are included in the subphylum Tunicata. (b) A Ciona intestinalis larva. This photograph was constructed by merging three photographs of the same individual. Scale bar: 100 μm. (c) Ciona intestinalis adults. After metamorphosis, Ciona loses its tail and starts to settle. Most ascidians are filter feeders.