How might avicularia and vibracula help protect a bryozoan colony?

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Eurystomella bilabiata, a moss animal from the Order Cheilostomata. — moss animal *Eurystomella bilabiata*, a moss animal from the Order Cheilostomata.

In bryozoan colonies, avicularia and vibracula are specialized types of zooids that serve protective and maintenance functions.

Avicularia: These zooids feature a modified operculum that acts as a jaw, powered by strong adductor muscles. In some species, such as Bugula, they are movable and resemble miniature birds' heads.
Vibracula: In these specialized zooids, the operculum has evolved into a long, whiplike seta (a hairlike projection).

While their exact functions are not fully understood, both avicularia and vibracula are believed to help protect the colony by keeping its surface clear of debris and epizoites—organisms that attempt to attach to the colony's surface without acting as parasites.1