Ascidians—Model Organisms

Ascidians represent an interesting model organism to study in various points of view. For many years, there has been a subject on discussion of taxonomic position of Urochordates. There are certain characters, which resemble both invertebrate and chordate. For example, the larval stage possess a notochord in the tail region which resembles the chordate characters, whereas the adult stage do not contains notochord, which is resemble the invertebrates.