Star ascidian  (Botryllus schlosseri)

All sea-squirts filter suspended particles from the water. They maintain a current that passes through their body by beating tiny hair-like structures known as 'cilia'; the water enters through an opening called the 'inhalant siphon', and passes through the pharynx, where plankton and detritus become trapped in mucus and are passed to the stomach. The water then passes out through a second opening called the 'exhalent siphon'. In the star ascidian, the exhalent siphons of all the members of the colony open into a shared chamber, known as the cloaca, water then passes out of a shared exhalent siphon at the centre of the colony (3).

In the star ascidian, the zooids are hermaphroditic(3); after fertilisation, eggs are retained until the tadpole larvae have formed (2). The larvae are then released through the exhalent siphon, and live in the water column for about 36 hours, before settling and forming new colonies (2). Asexual reproduction can also take place through budding(3). Colonies may live for up to one and a half years (3). Star ascidians are predated upon by cowries (members of the genus Trivia), which are gastropod molluscs; cowries also lay their eggs into holes made in the star-ascidian test (3).