About Bryozoa and Entoprocta

Bryozoans are often mistaken for other organisms, such as corals, hydroids and algae. They can act as substrates and habitats for other animals and, like corals, have a slow rate of growth. Once damaged they can take many years to re-grow.

History of Bryozoa

Guillaume Rondelet

The French naturalist Guillaume Rondelet (1507-1566) who wrote a great treatise on aquatic animals in 1556 entitled 'Libri de piscibus marinis in quibus verae piscium effigies expressae sunt'.

The first known bryozoan was described in 1555 by Guillaume Rondelet. Ferrante Imperato, a Naples apothecary, first hinted at the animal nature of bryozoans in 1599.

Not everyone was convinced, however, and the phyla oscillated between the plant and animal kingdoms for the next 250 years. Even the famous taxonomist Carl Linnaeus sat on the fence, placing them in an intermediate group called the Zoophyta (animal-plant) in 1758.

Today they are recognised as aquatic invertebrate animals.

'Sea Ragged Staffe' appears to be the first description of a bryozoan in English by the apothecary Thomas Johnson in 1632. This is known today as Alcyonidium diaphanum (Hudson, 1778).

Why are they important?

Bryozoans play an important role in many aquatic ecosystems. The collections support research into these areas:

Ocean acidification

Changes in ocean pH, caused by greater carbon dioxide in the atmosphere, will have a severe impact on all marine species that have calcium carbonate skeletons such as Bryozoa. A significant lowering of ocean pH could affect species' distribution, abundance and diversity, with associated knock-on impacts on food chains and ecosystems.

Bio fouling

'Fouling' occurs when organisms affect the performance or functioning of man-made structures. Animals, such as bryozoans, polychaetes, sea squirts, hydroids, barnacles and sponges, can foul oil rigs, buoys, moorings, current meters, ship hulls, intake pipes of power stations, and so on, causing encrusting and blockage problems.

Non-native species

Nonnative Schizoporella japonica

Schizoporella japonica on boat hull, Westray, Scotland © JS Porter.

A non-native species is one that establishes itself in a new region as a result of intentional or unintentional introduction by human activity. 

Some species that spread beyond their native range are not necessarily harmful, but others can displace native species and potentially cause economic and environmental damage. For example, the bryozoan Schizoporella japonica, which was originally described in Japan, has recently been found in the UK. It is likely that it was introduced here by an ocean-going vessel.

Parasite hosts

Myxozoan spores

Spores of Tetracapsuloides bryosalmonae, the myxozoan that causes PKD.

Some freshwater bryozoans act as hosts for certain myxozoan fish parasites that can cause proliferative kidney disease (PKD), a condition found in salmonid fishes.


Chemicals isolated from Bryozoa have been used to treat cancer and leukaemia. Bryostatins were first isolated from Bugula neritina in 1969, and more recent work has shown that the chemicals are actually produced by symbiotic bacteria on the bryozoan.

Some bryozoans can cause an allergic dermatitis. The ctenostome bryozoan, Alcyonidium diaphanum, causes a rash called 'Dogger Bank itch' that can result in large painful weeping blisters.