Phylum: Bryozoa (Moss Animals or Bryozoans)

"Bryozoans are filter feeding invertebrates and can be found in both freshwater and marine habitats, where they are often easy to miss because of their small size and cryptic lifestyle (e.g., encrusting seashells, rocks, or kelp). In almost all species, tiny (< 1-millimeter diameter) bryozoan individuals, called zooids, live together as a colony that often encrusts surfaces, grows branching structures, or, in freshwater species, forms a gelatinous blob. Despite their small size, marine bryozoans are abundant in many fossil assemblages thanks to the preservability of their hard calcium carbonate skeletons. To date, more than 17,800 species of fossil bryozoans have been described and more than 6,000 living species are known. The two primarily marine classes, Stenolaemata and Gymnolaemata, compose the majority of the fossil species, as species in the freshwater class Phylactolaemata do not produce a similarly robust skeleton that would be likely to fossilize...

The relationship of the bryozoans to other phyla has been revised on several occasions and continues to be an active area of research as more modern genetic data add new information. When originally described, the phylum was called “Polyzoa,” reflecting the colonial nature of this group. From 1831 onwards, the name bryozoan has been used; however, this name originally included an outwardly similar looking group, the Endoprocta. As it was noted in 1869 that these groups shared only a few, coarse external features, they were split as Endoprocta and Ectoprocta. These names are based on the position of the anus relative to the animals’ crown-like feeding apparatuses. In Ectoprocta, the anus is outside, and below the crown whereas the anus is positioned within the crown in the Endoprocta. Despite the splitting of the “bryozoa” into these two groups, the name bryozoa has continued to be used for the Ectoprocta."

Source: Smith, Jansen A. (2020). Bryozoa. In: The Digital Encyclopedia of Ancient Life. Available at: https://www.digitalatlasofancientlife.org/learn/bryozoa [Accessed on 11 July 2026]

Class: Gymnolaemata

Order: Cheilostomatida

Family: Adeonidae

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