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SEM of Conopeum seurati, an encrusting bryozoan. Photo by J. Winston, courtesy of the American Museum of Natural History. Used with permission.

Sketch of the growth pattern in C. seurati from the ancestrula (at center in blue) and subsequent proximal - distolateral budding pattern of growth. Drawing by J. Winston, courtesy of the American Museum of Natural History. Used with permission.

Species Name: Conopeum seurati Canu, 1908
Common Name: None
Synonymy: None

    Kingdom Phylum/Division Class: Order: Family: Genus:
    Animalia Ectoprocta Gymnolaemata Cheilostomata Membraniporidae Conopeum

    Voucher Specimen: American Museum of Natural History # 583
    Suborder: Anasca

    Species Description

    C. seurati is an encrusting bryozoan that forms small whitish colonies on seagrasses and other substrata. Zooids are oval in shape and measure approximately 0.55 X 0.33 mm. Each has a single pair of long, distal spines. Lateral spines, if present, are highly variable in number.

    The lophophore measures approximately 0.621 mm in diameter and bears an average of 15 tentacles. The proximal budding pattern of this species, which shows a distal-proximal pattern, sets it apart from most other members of its genus. In C. seurati, the ancestrula (the original settled larva) buds proximally. This proximal zooid then gives rise to 1 distal, and 2 distolateral zooids. The distolateral zooids then bud proximally, distally and laterally until a circle is formed around the ancestrula.

    Potentially Misidentified Species

    C. seurati could be mistaken for C. tenuissimum. However, the budding pattern in C. tenuissimum is slightly more regular than in C. seurati due to C. tenuissimum's somewhat larger zooid size and distal-proximal budding pattern. Additionally, lateral walls in individual zooids are more calcified in C. seurati, and its distal spines are longer and more pointed. C. seurati has fewer lateral spines than C. tenuissimum in water of the same salinity: 1 - 3 for C. seurati vs. 5 for C. tenuissimum.


    Regional Occurrence

    C. seurati typically occurs in Northern Europe and the Mediterranean. Prior to Winston's 1982 study, this species had not been reported in the western hemisphere. Its range now includes estuarine habitats on Florida's east coast.

    IRL Distribution

    C. seurati is likely to be widespread in the IRL, but it has been primarily collected from Link Port (Winston 1982).


    Age, Size, Lifespan

    Individual zooids measure an average of 0.55 X 0.33 mm in size. Lophophore diameter measures 0.621 on average.


    C. seurati is among the most abundant bryozoan species in the IRL. It is most common from December through May (Winston 1982). In the IRL, it is considered a fouling organism (Winston 1995).




    No ovicells are present in this species and eggs are not brooded. Reproduction is accomplished by releasing eggs into the water column for fertilization. Peak reproductive season occurs from late winter to early spring.

    C. seurati and C. tenuissimum co-occur in estuarine habitats, but their reproductive seasons are apparently offset. During December, when C. tenuissimum larvae are settling in their greatest numbers, they can outnumber C. seurati by a ratio of 99:1. However, throughout January, settlement rates between both species tend to equalize, and by May, only C. seurati is still settling.


    After fertilization, embryos develop into planktonic larvae.



    C. seurati is considered a winter species in the IRL, being most common from December through May (Winston 1982, 1995).


    C. seurati is one of 3 truly estuarine bryozoan species in the Indian River Lagoon. It was not collected from coastal stations, but was routinely collected in the IRL in waters where salinity ranged between 18 - 40 ‰ (Winston 1982, 1995). In Europe, it has been collected in estuaries where salinity is less than 1 ‰ (Winston 1982).


    Trophic Mode

    C. seurati, like all bryozoans, is a suspension feeder. Each individual zooid in a colony has an average of 15 ciliated tentacles that are extended to filter phytoplankton less than 0.045 mm in size (about 1/1800 of an inch) from the water column. Bullivant ( 1967; 1968) showed that the average individual zooid in a colony can clear 8.8 ml of water per day.


    Winston (1982) reported that C. seurati may be a better space competitor than C. tenuissimum, because its colonies were often observed to overgrow C. tenuissimum.


    Typical habitat for ectoprocts in the Indian River Lagoon include seagrasses, drift algae, oyster reef, dock, pilings, breakwaters, and man-made debris (Winston 1995).

    Associated Species

    Seagrasses as well as floating macroalgae, provide support for bryozoan colonies. In turn, bryozoans provide habitat for many species of juvenile fishes and their invertebrate prey such as polychaete worms, amphipods and copepods (Winston 1995). Bryozoans are also found in association with other species that act as support structures: mangrove roots, oyster beds, mussels, etc.


    Benefit in IRL

    Bryozoans are ecologically important in the Indian River Lagoon due to their feeding method. As suspension feeders, they act as living filters in the marine environment. For example, Winston (1995) reported that bryozoan colonies located in 1 square meter of seagrass bed could potentially filter and recirculate an average of 48,000 gallons of seawater per day.


    Winston JE. 1982. Marine bryozoans (Ectoprocta) of the Indian River area (Florida). Bull Amer Mus Nat Hist 173: 99-176.

    Winston JE. 1995. Ectoproct diversity of the Indian River coastal lagoon. Bull Mar Sci 57: 84-93.

Report by: K. Hill, Smithsonian Marine Station
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Page last updated: July 25, 2001

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