How do appendicularians differ from most adult tunicates?

Appendicularians, also known as larvaceans, differ significantly from most other adult tunicates in several key ways:

• Morphology: Unlike most adult tunicates, which undergo metamorphosis and lose many chordate features, the adult appendicularian retains a tadpole-like body that closely resembles the larval form of other tunicates.123
• Lifestyle: While many tunicates are benthic and sessile (bottom-dwelling and attached), appendicularians are free-swimming, pelagic animals that spend their entire lives in the open sea.423
• Anatomy: Appendicularians lack a distinct atrium, a structure typically found in other tunicates. Additionally, they do not form colonies, whereas many other tunicates, such as ascidians, often exist as colonial organisms.34
• Feeding: Appendicularians secrete a delicate, gelatinous "house" around their bodies, which they use to net microscopic food particles from the water. They are known to abandon and replace these structures multiple times each day.14