Tunicates, also called sea squirts or ascidian, belong to the subphylum Tunicata (also called Urochordata). These are soft-bodied animals that may be solitary, social (colonial clusters connected by tubes called stolons), or compound (colonial individuals embedded in a common outer covering). In all cases the animals are attached to a solid substrate, and have an incurrent siphon (opening for water to enter the body) and an excurrent siphon (for the filtered water to leave the body). The excurrent siphon may be shared in colonial species. Click here for more information.