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SEM of Crisia eburnea showing an enlarged gonozooid. Photo by J. Winston, courtesy of the American Museum of Natural History. Used with permission.

Species Name: Crisia eburnea Linnaeus, 1758
Common Name: None
Synonymy: Sertularia eburnea Linnaeus, 1758
Crisia eburnea Maturo, 1957
  1. TAXONOMY

    Kingdom Phylum/Division Class: Order: Family: Genus:
    Animalia Ectoprocta Gymnolaemata Cyclostomata Crisiidae Crisia

    Other Taxonomic Groupings

    Voucher Specimen: American Museum of American History # 632
    Suborder: Articulata

  2. HABITAT AND DISTRIBUTION

    Regional Occurrence

    C. eburnea is common in cold water areas from Europe through West Africa in the eastern Atlantic, and from Labrador to Florida in the western Atlantic.

    IRL Distribution

    C. eburnea occurs in the IRL in association with algae and seagrasses. Within the IRL, it has been reported only from around the Sebastian Inlet grass flats; however, it is likely to occur at other locations as well.

  3. LIFE HISTORY AND POPULATION BIOLOGY

    Age, Size, Lifespan

    Individual zooids measure 0.10 X 0.25 mm on average.

    Abundance

    Though C. eburnea is common throughout its range, Winston (1982) reported its occurrence only once, from the grass flats around Sebastian Inlet where it was found growing on the Rhodophyte Soliera tenera.

    Locomotion

    Sessile

    Embryology

    Gonozooids in C. eburnea generally occur between the fourth and fifth zooid of a fertile internode. They are elongate and roughly club shaped, but rounded distally. The oeciopore is a short tube with a transverse ovoid opening. Larvae emerging from the oeciopore remain on the parent colony briefly before entering the water column (Winston 1982).

  4. PHYSICAL TOLERANCES

    Temperature

    C. eburnea is eurythermal.

    Salinity

    Within the Indian River Lagoon, C. eburnea occurs where salinity exceeds 30‰.

  5. COMMUNITY ECOLOGY

    Trophic Mode

    C. eburnea, like all bryozoans, is a suspension feeder. Each individual zooid in a colony has 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.

    Habitats

    Typical habitat for ectoprocts in the Indian River Lagoon include seagrasses, drift algae, oyster reef, dock, pilings, breakwaters, and man-made debris (Winston 1995). C. eburnea occurs growing on algae, and ion seagrasses. In the IRL, it has been found growing in association with the red algae Solieria tenera.

    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.

  6. ADDITIONAL INFORMATION

    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.

  7. REFERENCES

    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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