Orange pumice bryozoan (Cellepora pumicosa)

Distribution data supplied by the Ocean Biodiversity Information System (OBIS). To interrogate UK data visit the NBN Atlas.Map Help



Cellepora pumicosa is an orange, encrusting bryozoan that begins as patches of orange and then develops into nodules or small mounds. The colonies often exceed 2 cm in diameter and form strong thick multiple-layered (multilaminar) cylinders around erect substratum such as other bryozoans. The individual zooids lie flat and curve convexly upwards into a hexagonal to oval shape that is commonly 0.5 to 0.7 mm by 0.3 to 0.5 mm in size, with distinct boundaries between zooids marked by shallow grooves. Surrounding the oval-shaped opening (orifice) there is a raised rim that extends to form an erect tube (peristome), from which the avicularium (a specialized zooid) extends and gives the colony a spikey appearance. There are no oral spines in this species.  The well-developed colonies have a distinctive knobby appearance with little of the frontal shield visible, due to the arrangement of the erect zooids. The brood chamber (ovicell) is spherical in shape and comes out above the thinly calcified peristome rim. It has four to six variably sized pores close to the opening in the frontal wall (aperture). The embryos are red and present all year round but are most common in the late summer. 

Recorded distribution in Britain and Ireland

Recorded around all British and Irish coasts with most records within in the southwest of the UK and the English Channel.

Global distribution

Recorded in the Mediterranean Sea off the coast of Greece, Egypt, Algeria, and Sardinia, along western Norway, in the Strait of Kara, and the Gulf of St. Lawrence, Canada.


Found from the kelp zone to offshore and on a range of hard or artificial substrata or other epifauna. 

Depth range

0 - 110 m (occasional records up to 190 m)

Identifying features

  • Begins as patches of orange and then develops into nodules or small mounds.
  • Colonies often exceed 2 cm in diameter.  
  • Embryos are red and most visible in the late summer. 
  • Spikey appearance due to the avicularium extending proximally from the raised peristome.  
  • No oral spines.  
  • Zooids are between 0.5 to 0.7 mm and 0.3 to 0.5 mm in size.  

Additional information


Listed by

- none -


  1. Hayward, P.J. & Ryland, J.S. 1999. Cheilostomatous Bryozoa. Part II Hippothooidea - Celleporoidea. London: Academic Press. [Synopses of the British Fauna, no. 14. (2nd edition)]

  2. Porter, J., 2012. Seasearch Guide to Bryozoans and Hydroids of Britain and Ireland.   Ross-on-Wye: Marine Conservation Society.


  1. NBN (National Biodiversity Network) Atlas. Available from:

  2. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. Accessed: 2024-04-25


This review can be cited as:

Burdett, E.G. 2023. Cellepora pumicosa Orange pumice bryozoan. In Tyler-Walters H. Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 25-04-2024]. Available from:

Last Updated: 04/10/2023