Ascidiacea, commonly known as sea squirts, are marine invertebrates belonging to the phylum Chordata. They are characterized by their sac-like bodies and are typically found attached to rocks, shells, or other surfaces in shallow waters. Sea squirts filter feed by drawing in water through an incurrent siphon, extracting plankton and organic particles, and expelling the filtered water through an excurrent siphon. These organisms exhibit two main life stages: a free-swimming larval stage and a sessile adult stage. The larvae possess a notochord and a dorsal nerve cord, which are key features of Chordata. As adults, they lose these structures and develop a simple body plan, making them an interesting subject for studying evolutionary biology.